Google Git
Sign in
android-kvm / linux / aa662fc04f5b290b3979332588bf8d812b189962 / . / drivers / gpu / drm / drm_vblank.c
blob: b18e1efbbae1aca2eb8618315975ed5fdcec33b9 [file] [log] [blame]
/*
* drm_irq.c IRQ and vblank support
*
* \author Rickard E. (Rik) Faith <faith@valinux.com>
* \author Gareth Hughes <gareth@valinux.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/moduleparam.h>
#include <drm/drm_crtc.h>
#include <drm/drm_drv.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_managed.h>
#include <drm/drm_modeset_helper_vtables.h>
#include <drm/drm_print.h>
#include <drm/drm_vblank.h>
#include "drm_internal.h"
#include "drm_trace.h"
/**
* DOC: vblank handling
*
* From the computer's perspective, every time the monitor displays
* a new frame the scanout engine has "scanned out" the display image
* from top to bottom, one row of pixels at a time. The current row
* of pixels is referred to as the current scanline.
*
* In addition to the display's visible area, there's usually a couple of
* extra scanlines which aren't actually displayed on the screen.
* These extra scanlines don't contain image data and are occasionally used
* for features like audio and infoframes. The region made up of these
* scanlines is referred to as the vertical blanking region, or vblank for
* short.
*
* For historical reference, the vertical blanking period was designed to
* give the electron gun (on CRTs) enough time to move back to the top of
* the screen to start scanning out the next frame. Similar for horizontal
* blanking periods. They were designed to give the electron gun enough
* time to move back to the other side of the screen to start scanning the
* next scanline.
*
* ::
*
*
* physical → ⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽
* top of | |
* display | |
* | New frame |
* | |
* |↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓|
* |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| ← Scanline,
* |↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓| updates the
* | | frame as it
* | | travels down
* | | ("sacn out")
* | Old frame |
* | |
* | |
* | |
* | | physical
* | | bottom of
* vertical |⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽| ← display
* blanking ┆xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx┆
* region → ┆xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx┆
* ┆xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx┆
* start of → ⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽
* new frame
*
* "Physical top of display" is the reference point for the high-precision/
* corrected timestamp.
*
* On a lot of display hardware, programming needs to take effect during the
* vertical blanking period so that settings like gamma, the image buffer
* buffer to be scanned out, etc. can safely be changed without showing
* any visual artifacts on the screen. In some unforgiving hardware, some of
* this programming has to both start and end in the same vblank. To help
* with the timing of the hardware programming, an interrupt is usually
* available to notify the driver when it can start the updating of registers.
* The interrupt is in this context named the vblank interrupt.
*
* The vblank interrupt may be fired at different points depending on the
* hardware. Some hardware implementations will fire the interrupt when the
* new frame start, other implementations will fire the interrupt at different
* points in time.
*
* Vertical blanking plays a major role in graphics rendering. To achieve
* tear-free display, users must synchronize page flips and/or rendering to
* vertical blanking. The DRM API offers ioctls to perform page flips
* synchronized to vertical blanking and wait for vertical blanking.
*
* The DRM core handles most of the vertical blanking management logic, which
* involves filtering out spurious interrupts, keeping race-free blanking
* counters, coping with counter wrap-around and resets and keeping use counts.
* It relies on the driver to generate vertical blanking interrupts and
* optionally provide a hardware vertical blanking counter.
*
* Drivers must initialize the vertical blanking handling core with a call to
* drm_vblank_init(). Minimally, a driver needs to implement
* &drm_crtc_funcs.enable_vblank and &drm_crtc_funcs.disable_vblank plus call
* drm_crtc_handle_vblank() in its vblank interrupt handler for working vblank
* support.
*
* Vertical blanking interrupts can be enabled by the DRM core or by drivers
* themselves (for instance to handle page flipping operations). The DRM core
* maintains a vertical blanking use count to ensure that the interrupts are not
* disabled while a user still needs them. To increment the use count, drivers
* call drm_crtc_vblank_get() and release the vblank reference again with
* drm_crtc_vblank_put(). In between these two calls vblank interrupts are
* guaranteed to be enabled.
*
* On many hardware disabling the vblank interrupt cannot be done in a race-free
* manner, see &drm_driver.vblank_disable_immediate and
* &drm_driver.max_vblank_count. In that case the vblank core only disables the
* vblanks after a timer has expired, which can be configured through the
* ``vblankoffdelay`` module parameter.
*
* Drivers for hardware without support for vertical-blanking interrupts
* must not call drm_vblank_init(). For such drivers, atomic helpers will
* automatically generate fake vblank events as part of the display update.
* This functionality also can be controlled by the driver by enabling and
* disabling struct drm_crtc_state.no_vblank.
*/
/* Retry timestamp calculation up to 3 times to satisfy
* drm_timestamp_precision before giving up.
*/
#define DRM_TIMESTAMP_MAXRETRIES 3
/* Threshold in nanoseconds for detection of redundant
* vblank irq in drm_handle_vblank(). 1 msec should be ok.
*/
#define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000
static bool
drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
ktime_t *tvblank, bool in_vblank_irq);
static unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */
static int drm_vblank_offdelay = 5000; /* Default to 5000 msecs. */
module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs] (0: never disable, <0: disable immediately)");
MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
static void store_vblank(struct drm_device *dev, unsigned int pipe,
u32 vblank_count_inc,
ktime_t t_vblank, u32 last)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
assert_spin_locked(&dev->vblank_time_lock);
vblank->last = last;
write_seqlock(&vblank->seqlock);
vblank->time = t_vblank;
atomic64_add(vblank_count_inc, &vblank->count);
write_sequnlock(&vblank->seqlock);
}
static u32 drm_max_vblank_count(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
return vblank->max_vblank_count ?: dev->max_vblank_count;
}
/*
* "No hw counter" fallback implementation of .get_vblank_counter() hook,
* if there is no useable hardware frame counter available.
*/
static u32 drm_vblank_no_hw_counter(struct drm_device *dev, unsigned int pipe)
{
drm_WARN_ON_ONCE(dev, drm_max_vblank_count(dev, pipe) != 0);
return 0;
}
static u32 __get_vblank_counter(struct drm_device *dev, unsigned int pipe)
{
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
if (drm_WARN_ON(dev, !crtc))
return 0;
if (crtc->funcs->get_vblank_counter)
return crtc->funcs->get_vblank_counter(crtc);
} else if (dev->driver->get_vblank_counter) {
return dev->driver->get_vblank_counter(dev, pipe);
}
return drm_vblank_no_hw_counter(dev, pipe);
}
/*
* Reset the stored timestamp for the current vblank count to correspond
* to the last vblank occurred.
*
* Only to be called from drm_crtc_vblank_on().
*
* Note: caller must hold &drm_device.vbl_lock since this reads & writes
* device vblank fields.
*/
static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe)
{
u32 cur_vblank;
bool rc;
ktime_t t_vblank;
int count = DRM_TIMESTAMP_MAXRETRIES;
spin_lock(&dev->vblank_time_lock);
/*
* sample the current counter to avoid random jumps
* when drm_vblank_enable() applies the diff
*/
do {
cur_vblank = __get_vblank_counter(dev, pipe);
rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, false);
} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
/*
* Only reinitialize corresponding vblank timestamp if high-precision query
* available and didn't fail. Otherwise reinitialize delayed at next vblank
* interrupt and assign 0 for now, to mark the vblanktimestamp as invalid.
*/
if (!rc)
t_vblank = 0;
/*
* +1 to make sure user will never see the same
* vblank counter value before and after a modeset
*/
store_vblank(dev, pipe, 1, t_vblank, cur_vblank);
spin_unlock(&dev->vblank_time_lock);
}
/*
* Call back into the driver to update the appropriate vblank counter
* (specified by @pipe). Deal with wraparound, if it occurred, and
* update the last read value so we can deal with wraparound on the next
* call if necessary.
*
* Only necessary when going from off->on, to account for frames we
* didn't get an interrupt for.
*
* Note: caller must hold &drm_device.vbl_lock since this reads & writes
* device vblank fields.
*/
static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
bool in_vblank_irq)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
u32 cur_vblank, diff;
bool rc;
ktime_t t_vblank;
int count = DRM_TIMESTAMP_MAXRETRIES;
int framedur_ns = vblank->framedur_ns;
u32 max_vblank_count = drm_max_vblank_count(dev, pipe);
/*
* Interrupts were disabled prior to this call, so deal with counter
* wrap if needed.
* NOTE! It's possible we lost a full dev->max_vblank_count + 1 events
* here if the register is small or we had vblank interrupts off for
* a long time.
*
* We repeat the hardware vblank counter & timestamp query until
* we get consistent results. This to prevent races between gpu
* updating its hardware counter while we are retrieving the
* corresponding vblank timestamp.
*/
do {
cur_vblank = __get_vblank_counter(dev, pipe);
rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, in_vblank_irq);
} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
if (max_vblank_count) {
/* trust the hw counter when it's around */
diff = (cur_vblank - vblank->last) & max_vblank_count;
} else if (rc && framedur_ns) {
u64 diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time));
/*
* Figure out how many vblanks we've missed based
* on the difference in the timestamps and the
* frame/field duration.
*/
drm_dbg_vbl(dev, "crtc %u: Calculating number of vblanks."
" diff_ns = %lld, framedur_ns = %d)\n",
pipe, (long long)diff_ns, framedur_ns);
diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
if (diff == 0 && in_vblank_irq)
drm_dbg_vbl(dev, "crtc %u: Redundant vblirq ignored\n",
pipe);
} else {
/* some kind of default for drivers w/o accurate vbl timestamping */
diff = in_vblank_irq ? 1 : 0;
}
/*
* Within a drm_vblank_pre_modeset - drm_vblank_post_modeset
* interval? If so then vblank irqs keep running and it will likely
* happen that the hardware vblank counter is not trustworthy as it
* might reset at some point in that interval and vblank timestamps
* are not trustworthy either in that interval. Iow. this can result
* in a bogus diff >> 1 which must be avoided as it would cause
* random large forward jumps of the software vblank counter.
*/
if (diff > 1 && (vblank->inmodeset & 0x2)) {
drm_dbg_vbl(dev,
"clamping vblank bump to 1 on crtc %u: diffr=%u"
" due to pre-modeset.\n", pipe, diff);
diff = 1;
}
drm_dbg_vbl(dev, "updating vblank count on crtc %u:"
" current=%llu, diff=%u, hw=%u hw_last=%u\n",
pipe, (unsigned long long)atomic64_read(&vblank->count),
diff, cur_vblank, vblank->last);
if (diff == 0) {
drm_WARN_ON_ONCE(dev, cur_vblank != vblank->last);
return;
}
/*
* Only reinitialize corresponding vblank timestamp if high-precision query
* available and didn't fail, or we were called from the vblank interrupt.
* Otherwise reinitialize delayed at next vblank interrupt and assign 0
* for now, to mark the vblanktimestamp as invalid.
*/
if (!rc && !in_vblank_irq)
t_vblank = 0;
store_vblank(dev, pipe, diff, t_vblank, cur_vblank);
}
u64 drm_vblank_count(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
u64 count;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return 0;
count = atomic64_read(&vblank->count);
/*
* This read barrier corresponds to the implicit write barrier of the
* write seqlock in store_vblank(). Note that this is the only place
* where we need an explicit barrier, since all other access goes
* through drm_vblank_count_and_time(), which already has the required
* read barrier curtesy of the read seqlock.
*/
smp_rmb();
return count;
}
/**
* drm_crtc_accurate_vblank_count - retrieve the master vblank counter
* @crtc: which counter to retrieve
*
* This function is similar to drm_crtc_vblank_count() but this function
* interpolates to handle a race with vblank interrupts using the high precision
* timestamping support.
*
* This is mostly useful for hardware that can obtain the scanout position, but
* doesn't have a hardware frame counter.
*/
u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
u64 vblank;
unsigned long flags;
drm_WARN_ONCE(dev, drm_debug_enabled(DRM_UT_VBL) &&
!crtc->funcs->get_vblank_timestamp,
"This function requires support for accurate vblank timestamps.");
spin_lock_irqsave(&dev->vblank_time_lock, flags);
drm_update_vblank_count(dev, pipe, false);
vblank = drm_vblank_count(dev, pipe);
spin_unlock_irqrestore(&dev->vblank_time_lock, flags);
return vblank;
}
EXPORT_SYMBOL(drm_crtc_accurate_vblank_count);
static void __disable_vblank(struct drm_device *dev, unsigned int pipe)
{
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
if (drm_WARN_ON(dev, !crtc))
return;
if (crtc->funcs->disable_vblank)
crtc->funcs->disable_vblank(crtc);
} else {
dev->driver->disable_vblank(dev, pipe);
}
}
/*
* Disable vblank irq's on crtc, make sure that last vblank count
* of hardware and corresponding consistent software vblank counter
* are preserved, even if there are any spurious vblank irq's after
* disable.
*/
void drm_vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
assert_spin_locked(&dev->vbl_lock);
/* Prevent vblank irq processing while disabling vblank irqs,
* so no updates of timestamps or count can happen after we've
* disabled. Needed to prevent races in case of delayed irq's.
*/
spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
/*
* Update vblank count and disable vblank interrupts only if the
* interrupts were enabled. This avoids calling the ->disable_vblank()
* operation in atomic context with the hardware potentially runtime
* suspended.
*/
if (!vblank->enabled)
goto out;
/*
* Update the count and timestamp to maintain the
* appearance that the counter has been ticking all along until
* this time. This makes the count account for the entire time
* between drm_crtc_vblank_on() and drm_crtc_vblank_off().
*/
drm_update_vblank_count(dev, pipe, false);
__disable_vblank(dev, pipe);
vblank->enabled = false;
out:
spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
}
static void vblank_disable_fn(struct timer_list *t)
{
struct drm_vblank_crtc *vblank = from_timer(vblank, t, disable_timer);
struct drm_device *dev = vblank->dev;
unsigned int pipe = vblank->pipe;
unsigned long irqflags;
spin_lock_irqsave(&dev->vbl_lock, irqflags);
if (atomic_read(&vblank->refcount) == 0 && vblank->enabled) {
drm_dbg_core(dev, "disabling vblank on crtc %u\n", pipe);
drm_vblank_disable_and_save(dev, pipe);
}
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
}
static void drm_vblank_init_release(struct drm_device *dev, void *ptr)
{
struct drm_vblank_crtc *vblank = ptr;
drm_WARN_ON(dev, READ_ONCE(vblank->enabled) &&
drm_core_check_feature(dev, DRIVER_MODESET));
drm_vblank_destroy_worker(vblank);
del_timer_sync(&vblank->disable_timer);
}
/**
* drm_vblank_init - initialize vblank support
* @dev: DRM device
* @num_crtcs: number of CRTCs supported by @dev
*
* This function initializes vblank support for @num_crtcs display pipelines.
* Cleanup is handled automatically through a cleanup function added with
* drmm_add_action_or_reset().
*
* Returns:
* Zero on success or a negative error code on failure.
*/
int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
{
int ret;
unsigned int i;
spin_lock_init(&dev->vbl_lock);
spin_lock_init(&dev->vblank_time_lock);
dev->vblank = drmm_kcalloc(dev, num_crtcs, sizeof(*dev->vblank), GFP_KERNEL);
if (!dev->vblank)
return -ENOMEM;
dev->num_crtcs = num_crtcs;
for (i = 0; i < num_crtcs; i++) {
struct drm_vblank_crtc *vblank = &dev->vblank[i];
vblank->dev = dev;
vblank->pipe = i;
init_waitqueue_head(&vblank->queue);
timer_setup(&vblank->disable_timer, vblank_disable_fn, 0);
seqlock_init(&vblank->seqlock);
ret = drmm_add_action_or_reset(dev, drm_vblank_init_release,
vblank);
if (ret)
return ret;
ret = drm_vblank_worker_init(vblank);
if (ret)
return ret;
}
return 0;
}
EXPORT_SYMBOL(drm_vblank_init);
/**
* drm_dev_has_vblank - test if vblanking has been initialized for
* a device
* @dev: the device
*
* Drivers may call this function to test if vblank support is
* initialized for a device. For most hardware this means that vblanking
* can also be enabled.
*
* Atomic helpers use this function to initialize
* &drm_crtc_state.no_vblank. See also drm_atomic_helper_check_modeset().
*
* Returns:
* True if vblanking has been initialized for the given device, false
* otherwise.
*/
bool drm_dev_has_vblank(const struct drm_device *dev)
{
return dev->num_crtcs != 0;
}
EXPORT_SYMBOL(drm_dev_has_vblank);
/**
* drm_crtc_vblank_waitqueue - get vblank waitqueue for the CRTC
* @crtc: which CRTC's vblank waitqueue to retrieve
*
* This function returns a pointer to the vblank waitqueue for the CRTC.
* Drivers can use this to implement vblank waits using wait_event() and related
* functions.
*/
wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc)
{
return &crtc->dev->vblank[drm_crtc_index(crtc)].queue;
}
EXPORT_SYMBOL(drm_crtc_vblank_waitqueue);
/**
* drm_calc_timestamping_constants - calculate vblank timestamp constants
* @crtc: drm_crtc whose timestamp constants should be updated.
* @mode: display mode containing the scanout timings
*
* Calculate and store various constants which are later needed by vblank and
* swap-completion timestamping, e.g, by
* drm_crtc_vblank_helper_get_vblank_timestamp(). They are derived from
* CRTC's true scanout timing, so they take things like panel scaling or
* other adjustments into account.
*/
void drm_calc_timestamping_constants(struct drm_crtc *crtc,
const struct drm_display_mode *mode)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int linedur_ns = 0, framedur_ns = 0;
int dotclock = mode->crtc_clock;
if (!drm_dev_has_vblank(dev))
return;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
/* Valid dotclock? */
if (dotclock > 0) {
int frame_size = mode->crtc_htotal * mode->crtc_vtotal;
/*
* Convert scanline length in pixels and video
* dot clock to line duration and frame duration
* in nanoseconds:
*/
linedur_ns = div_u64((u64) mode->crtc_htotal * 1000000, dotclock);
framedur_ns = div_u64((u64) frame_size * 1000000, dotclock);
/*
* Fields of interlaced scanout modes are only half a frame duration.
*/
if (mode->flags & DRM_MODE_FLAG_INTERLACE)
framedur_ns /= 2;
} else {
drm_err(dev, "crtc %u: Can't calculate constants, dotclock = 0!\n",
crtc->base.id);
}
vblank->linedur_ns = linedur_ns;
vblank->framedur_ns = framedur_ns;
vblank->hwmode = *mode;
drm_dbg_core(dev,
"crtc %u: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
crtc->base.id, mode->crtc_htotal,
mode->crtc_vtotal, mode->crtc_vdisplay);
drm_dbg_core(dev, "crtc %u: clock %d kHz framedur %d linedur %d\n",
crtc->base.id, dotclock, framedur_ns, linedur_ns);
}
EXPORT_SYMBOL(drm_calc_timestamping_constants);
/**
* drm_crtc_vblank_helper_get_vblank_timestamp_internal - precise vblank
* timestamp helper
* @crtc: CRTC whose vblank timestamp to retrieve
* @max_error: Desired maximum allowable error in timestamps (nanosecs)
* On return contains true maximum error of timestamp
* @vblank_time: Pointer to time which should receive the timestamp
* @in_vblank_irq:
* True when called from drm_crtc_handle_vblank(). Some drivers
* need to apply some workarounds for gpu-specific vblank irq quirks
* if flag is set.
* @get_scanout_position:
* Callback function to retrieve the scanout position. See
* @struct drm_crtc_helper_funcs.get_scanout_position.
*
* Implements calculation of exact vblank timestamps from given drm_display_mode
* timings and current video scanout position of a CRTC.
*
* The current implementation only handles standard video modes. For double scan
* and interlaced modes the driver is supposed to adjust the hardware mode
* (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to
* match the scanout position reported.
*
* Note that atomic drivers must call drm_calc_timestamping_constants() before
* enabling a CRTC. The atomic helpers already take care of that in
* drm_atomic_helper_update_legacy_modeset_state().
*
* Returns:
*
* Returns true on success, and false on failure, i.e. when no accurate
* timestamp could be acquired.
*/
bool
drm_crtc_vblank_helper_get_vblank_timestamp_internal(
struct drm_crtc *crtc, int *max_error, ktime_t *vblank_time,
bool in_vblank_irq,
drm_vblank_get_scanout_position_func get_scanout_position)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = crtc->index;
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
struct timespec64 ts_etime, ts_vblank_time;
ktime_t stime, etime;
bool vbl_status;
const struct drm_display_mode *mode;
int vpos, hpos, i;
int delta_ns, duration_ns;
if (pipe >= dev->num_crtcs) {
drm_err(dev, "Invalid crtc %u\n", pipe);
return false;
}
/* Scanout position query not supported? Should not happen. */
if (!get_scanout_position) {
drm_err(dev, "Called from CRTC w/o get_scanout_position()!?\n");
return false;
}
if (drm_drv_uses_atomic_modeset(dev))
mode = &vblank->hwmode;
else
mode = &crtc->hwmode;
/* If mode timing undefined, just return as no-op:
* Happens during initial modesetting of a crtc.
*/
if (mode->crtc_clock == 0) {
drm_dbg_core(dev, "crtc %u: Noop due to uninitialized mode.\n",
pipe);
drm_WARN_ON_ONCE(dev, drm_drv_uses_atomic_modeset(dev));
return false;
}
/* Get current scanout position with system timestamp.
* Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
* if single query takes longer than max_error nanoseconds.
*
* This guarantees a tight bound on maximum error if
* code gets preempted or delayed for some reason.
*/
for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
/*
* Get vertical and horizontal scanout position vpos, hpos,
* and bounding timestamps stime, etime, pre/post query.
*/
vbl_status = get_scanout_position(crtc, in_vblank_irq,
&vpos, &hpos,
&stime, &etime,
mode);
/* Return as no-op if scanout query unsupported or failed. */
if (!vbl_status) {
drm_dbg_core(dev,
"crtc %u : scanoutpos query failed.\n",
pipe);
return false;
}
/* Compute uncertainty in timestamp of scanout position query. */
duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime);
/* Accept result with < max_error nsecs timing uncertainty. */
if (duration_ns <= *max_error)
break;
}
/* Noisy system timing? */
if (i == DRM_TIMESTAMP_MAXRETRIES) {
drm_dbg_core(dev,
"crtc %u: Noisy timestamp %d us > %d us [%d reps].\n",
pipe, duration_ns / 1000, *max_error / 1000, i);
}
/* Return upper bound of timestamp precision error. */
*max_error = duration_ns;
/* Convert scanout position into elapsed time at raw_time query
* since start of scanout at first display scanline. delta_ns
* can be negative if start of scanout hasn't happened yet.
*/
delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos),
mode->crtc_clock);
/* Subtract time delta from raw timestamp to get final
* vblank_time timestamp for end of vblank.
*/
*vblank_time = ktime_sub_ns(etime, delta_ns);
if (!drm_debug_enabled(DRM_UT_VBL))
return true;
ts_etime = ktime_to_timespec64(etime);
ts_vblank_time = ktime_to_timespec64(*vblank_time);
drm_dbg_vbl(dev,
"crtc %u : v p(%d,%d)@ %lld.%06ld -> %lld.%06ld [e %d us, %d rep]\n",
pipe, hpos, vpos,
(u64)ts_etime.tv_sec, ts_etime.tv_nsec / 1000,
(u64)ts_vblank_time.tv_sec, ts_vblank_time.tv_nsec / 1000,
duration_ns / 1000, i);
return true;
}
EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp_internal);
/**
* drm_crtc_vblank_helper_get_vblank_timestamp - precise vblank timestamp
* helper
* @crtc: CRTC whose vblank timestamp to retrieve
* @max_error: Desired maximum allowable error in timestamps (nanosecs)
* On return contains true maximum error of timestamp
* @vblank_time: Pointer to time which should receive the timestamp
* @in_vblank_irq:
* True when called from drm_crtc_handle_vblank(). Some drivers
* need to apply some workarounds for gpu-specific vblank irq quirks
* if flag is set.
*
* Implements calculation of exact vblank timestamps from given drm_display_mode
* timings and current video scanout position of a CRTC. This can be directly
* used as the &drm_crtc_funcs.get_vblank_timestamp implementation of a kms
* driver if &drm_crtc_helper_funcs.get_scanout_position is implemented.
*
* The current implementation only handles standard video modes. For double scan
* and interlaced modes the driver is supposed to adjust the hardware mode
* (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to
* match the scanout position reported.
*
* Note that atomic drivers must call drm_calc_timestamping_constants() before
* enabling a CRTC. The atomic helpers already take care of that in
* drm_atomic_helper_update_legacy_modeset_state().
*
* Returns:
*
* Returns true on success, and false on failure, i.e. when no accurate
* timestamp could be acquired.
*/
bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
int *max_error,
ktime_t *vblank_time,
bool in_vblank_irq)
{
return drm_crtc_vblank_helper_get_vblank_timestamp_internal(
crtc, max_error, vblank_time, in_vblank_irq,
crtc->helper_private->get_scanout_position);
}
EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp);
/**
* drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
* vblank interval
* @dev: DRM device
* @pipe: index of CRTC whose vblank timestamp to retrieve
* @tvblank: Pointer to target time which should receive the timestamp
* @in_vblank_irq:
* True when called from drm_crtc_handle_vblank(). Some drivers
* need to apply some workarounds for gpu-specific vblank irq quirks
* if flag is set.
*
* Fetches the system timestamp corresponding to the time of the most recent
* vblank interval on specified CRTC. May call into kms-driver to
* compute the timestamp with a high-precision GPU specific method.
*
* Returns zero if timestamp originates from uncorrected do_gettimeofday()
* call, i.e., it isn't very precisely locked to the true vblank.
*
* Returns:
* True if timestamp is considered to be very precise, false otherwise.
*/
static bool
drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
ktime_t *tvblank, bool in_vblank_irq)
{
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
bool ret = false;
/* Define requested maximum error on timestamps (nanoseconds). */
int max_error = (int) drm_timestamp_precision * 1000;
/* Query driver if possible and precision timestamping enabled. */
if (crtc && crtc->funcs->get_vblank_timestamp && max_error > 0) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
ret = crtc->funcs->get_vblank_timestamp(crtc, &max_error,
tvblank, in_vblank_irq);
}
/* GPU high precision timestamp query unsupported or failed.
* Return current monotonic/gettimeofday timestamp as best estimate.
*/
if (!ret)
*tvblank = ktime_get();
return ret;
}
/**
* drm_crtc_vblank_count - retrieve "cooked" vblank counter value
* @crtc: which counter to retrieve
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity. Note that this timer isn't correct against a racing
* vblank interrupt (since it only reports the software vblank counter), see
* drm_crtc_accurate_vblank_count() for such use-cases.
*
* Note that for a given vblank counter value drm_crtc_handle_vblank()
* and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
* provide a barrier: Any writes done before calling
* drm_crtc_handle_vblank() will be visible to callers of the later
* functions, iff the vblank count is the same or a later one.
*
* See also &drm_vblank_crtc.count.
*
* Returns:
* The software vblank counter.
*/
u64 drm_crtc_vblank_count(struct drm_crtc *crtc)
{
return drm_vblank_count(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_count);
/**
* drm_vblank_count_and_time - retrieve "cooked" vblank counter value and the
* system timestamp corresponding to that vblank counter value.
* @dev: DRM device
* @pipe: index of CRTC whose counter to retrieve
* @vblanktime: Pointer to ktime_t to receive the vblank timestamp.
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity. Returns corresponding system timestamp of the time
* of the vblank interval that corresponds to the current vblank counter value.
*
* This is the legacy version of drm_crtc_vblank_count_and_time().
*/
static u64 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe,
ktime_t *vblanktime)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
u64 vblank_count;
unsigned int seq;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs)) {
*vblanktime = 0;
return 0;
}
do {
seq = read_seqbegin(&vblank->seqlock);
vblank_count = atomic64_read(&vblank->count);
*vblanktime = vblank->time;
} while (read_seqretry(&vblank->seqlock, seq));
return vblank_count;
}
/**
* drm_crtc_vblank_count_and_time - retrieve "cooked" vblank counter value
* and the system timestamp corresponding to that vblank counter value
* @crtc: which counter to retrieve
* @vblanktime: Pointer to time to receive the vblank timestamp.
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity. Returns corresponding system timestamp of the time
* of the vblank interval that corresponds to the current vblank counter value.
*
* Note that for a given vblank counter value drm_crtc_handle_vblank()
* and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
* provide a barrier: Any writes done before calling
* drm_crtc_handle_vblank() will be visible to callers of the later
* functions, iff the vblank count is the same or a later one.
*
* See also &drm_vblank_crtc.count.
*/
u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
ktime_t *vblanktime)
{
return drm_vblank_count_and_time(crtc->dev, drm_crtc_index(crtc),
vblanktime);
}
EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
static void send_vblank_event(struct drm_device *dev,
struct drm_pending_vblank_event *e,
u64 seq, ktime_t now)
{
struct timespec64 tv;
switch (e->event.base.type) {
case DRM_EVENT_VBLANK:
case DRM_EVENT_FLIP_COMPLETE:
tv = ktime_to_timespec64(now);
e->event.vbl.sequence = seq;
/*
* e->event is a user space structure, with hardcoded unsigned
* 32-bit seconds/microseconds. This is safe as we always use
* monotonic timestamps since linux-4.15
*/
e->event.vbl.tv_sec = tv.tv_sec;
e->event.vbl.tv_usec = tv.tv_nsec / 1000;
break;
case DRM_EVENT_CRTC_SEQUENCE:
if (seq)
e->event.seq.sequence = seq;
e->event.seq.time_ns = ktime_to_ns(now);
break;
}
trace_drm_vblank_event_delivered(e->base.file_priv, e->pipe, seq);
drm_send_event_locked(dev, &e->base);
}
/**
* drm_crtc_arm_vblank_event - arm vblank event after pageflip
* @crtc: the source CRTC of the vblank event
* @e: the event to send
*
* A lot of drivers need to generate vblank events for the very next vblank
* interrupt. For example when the page flip interrupt happens when the page
* flip gets armed, but not when it actually executes within the next vblank
* period. This helper function implements exactly the required vblank arming
* behaviour.
*
* NOTE: Drivers using this to send out the &drm_crtc_state.event as part of an
* atomic commit must ensure that the next vblank happens at exactly the same
* time as the atomic commit is committed to the hardware. This function itself
* does **not** protect against the next vblank interrupt racing with either this
* function call or the atomic commit operation. A possible sequence could be:
*
* 1. Driver commits new hardware state into vblank-synchronized registers.
* 2. A vblank happens, committing the hardware state. Also the corresponding
* vblank interrupt is fired off and fully processed by the interrupt
* handler.
* 3. The atomic commit operation proceeds to call drm_crtc_arm_vblank_event().
* 4. The event is only send out for the next vblank, which is wrong.
*
* An equivalent race can happen when the driver calls
* drm_crtc_arm_vblank_event() before writing out the new hardware state.
*
* The only way to make this work safely is to prevent the vblank from firing
* (and the hardware from committing anything else) until the entire atomic
* commit sequence has run to completion. If the hardware does not have such a
* feature (e.g. using a "go" bit), then it is unsafe to use this functions.
* Instead drivers need to manually send out the event from their interrupt
* handler by calling drm_crtc_send_vblank_event() and make sure that there's no
* possible race with the hardware committing the atomic update.
*
* Caller must hold a vblank reference for the event @e acquired by a
* drm_crtc_vblank_get(), which will be dropped when the next vblank arrives.
*/
void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
struct drm_pending_vblank_event *e)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
assert_spin_locked(&dev->event_lock);
e->pipe = pipe;
e->sequence = drm_crtc_accurate_vblank_count(crtc) + 1;
list_add_tail(&e->base.link, &dev->vblank_event_list);
}
EXPORT_SYMBOL(drm_crtc_arm_vblank_event);
/**
* drm_crtc_send_vblank_event - helper to send vblank event after pageflip
* @crtc: the source CRTC of the vblank event
* @e: the event to send
*
* Updates sequence # and timestamp on event for the most recently processed
* vblank, and sends it to userspace. Caller must hold event lock.
*
* See drm_crtc_arm_vblank_event() for a helper which can be used in certain
* situation, especially to send out events for atomic commit operations.
*/
void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
struct drm_pending_vblank_event *e)
{
struct drm_device *dev = crtc->dev;
u64 seq;
unsigned int pipe = drm_crtc_index(crtc);
ktime_t now;
if (drm_dev_has_vblank(dev)) {
seq = drm_vblank_count_and_time(dev, pipe, &now);
} else {
seq = 0;
now = ktime_get();
}
e->pipe = pipe;
send_vblank_event(dev, e, seq, now);
}
EXPORT_SYMBOL(drm_crtc_send_vblank_event);
static int __enable_vblank(struct drm_device *dev, unsigned int pipe)
{
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
if (drm_WARN_ON(dev, !crtc))
return 0;
if (crtc->funcs->enable_vblank)
return crtc->funcs->enable_vblank(crtc);
} else if (dev->driver->enable_vblank) {
return dev->driver->enable_vblank(dev, pipe);
}
return -EINVAL;
}
static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int ret = 0;
assert_spin_locked(&dev->vbl_lock);
spin_lock(&dev->vblank_time_lock);
if (!vblank->enabled) {
/*
* Enable vblank irqs under vblank_time_lock protection.
* All vblank count & timestamp updates are held off
* until we are done reinitializing master counter and
* timestamps. Filtercode in drm_handle_vblank() will
* prevent double-accounting of same vblank interval.
*/
ret = __enable_vblank(dev, pipe);
drm_dbg_core(dev, "enabling vblank on crtc %u, ret: %d\n",
pipe, ret);
if (ret) {
atomic_dec(&vblank->refcount);
} else {
drm_update_vblank_count(dev, pipe, 0);
/* drm_update_vblank_count() includes a wmb so we just
* need to ensure that the compiler emits the write
* to mark the vblank as enabled after the call
* to drm_update_vblank_count().
*/
WRITE_ONCE(vblank->enabled, true);
}
}
spin_unlock(&dev->vblank_time_lock);
return ret;
}
int drm_vblank_get(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
int ret = 0;
if (!drm_dev_has_vblank(dev))
return -EINVAL;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return -EINVAL;
spin_lock_irqsave(&dev->vbl_lock, irqflags);
/* Going from 0->1 means we have to enable interrupts again */
if (atomic_add_return(1, &vblank->refcount) == 1) {
ret = drm_vblank_enable(dev, pipe);
} else {
if (!vblank->enabled) {
atomic_dec(&vblank->refcount);
ret = -EINVAL;
}
}
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
return ret;
}
/**
* drm_crtc_vblank_get - get a reference count on vblank events
* @crtc: which CRTC to own
*
* Acquire a reference count on vblank events to avoid having them disabled
* while in use.
*
* Returns:
* Zero on success or a negative error code on failure.
*/
int drm_crtc_vblank_get(struct drm_crtc *crtc)
{
return drm_vblank_get(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_get);
void drm_vblank_put(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
if (drm_WARN_ON(dev, atomic_read(&vblank->refcount) == 0))
return;
/* Last user schedules interrupt disable */
if (atomic_dec_and_test(&vblank->refcount)) {
if (drm_vblank_offdelay == 0)
return;
else if (drm_vblank_offdelay < 0)
vblank_disable_fn(&vblank->disable_timer);
else if (!dev->vblank_disable_immediate)
mod_timer(&vblank->disable_timer,
jiffies + ((drm_vblank_offdelay * HZ)/1000));
}
}
/**
* drm_crtc_vblank_put - give up ownership of vblank events
* @crtc: which counter to give up
*
* Release ownership of a given vblank counter, turning off interrupts
* if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
*/
void drm_crtc_vblank_put(struct drm_crtc *crtc)
{
drm_vblank_put(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_put);
/**
* drm_wait_one_vblank - wait for one vblank
* @dev: DRM device
* @pipe: CRTC index
*
* This waits for one vblank to pass on @pipe, using the irq driver interfaces.
* It is a failure to call this when the vblank irq for @pipe is disabled, e.g.
* due to lack of driver support or because the crtc is off.
*
* This is the legacy version of drm_crtc_wait_one_vblank().
*/
void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int ret;
u64 last;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
ret = drm_vblank_get(dev, pipe);
if (drm_WARN(dev, ret, "vblank not available on crtc %i, ret=%i\n",
pipe, ret))
return;
last = drm_vblank_count(dev, pipe);
ret = wait_event_timeout(vblank->queue,
last != drm_vblank_count(dev, pipe),
msecs_to_jiffies(100));
drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n", pipe);
drm_vblank_put(dev, pipe);
}
EXPORT_SYMBOL(drm_wait_one_vblank);
/**
* drm_crtc_wait_one_vblank - wait for one vblank
* @crtc: DRM crtc
*
* This waits for one vblank to pass on @crtc, using the irq driver interfaces.
* It is a failure to call this when the vblank irq for @crtc is disabled, e.g.
* due to lack of driver support or because the crtc is off.
*/
void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
{
drm_wait_one_vblank(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_wait_one_vblank);
/**
* drm_crtc_vblank_off - disable vblank events on a CRTC
* @crtc: CRTC in question
*
* Drivers can use this function to shut down the vblank interrupt handling when
* disabling a crtc. This function ensures that the latest vblank frame count is
* stored so that drm_vblank_on can restore it again.
*
* Drivers must use this function when the hardware vblank counter can get
* reset, e.g. when suspending or disabling the @crtc in general.
*/
void drm_crtc_vblank_off(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
struct drm_pending_vblank_event *e, *t;
ktime_t now;
u64 seq;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
/*
* Grab event_lock early to prevent vblank work from being scheduled
* while we're in the middle of shutting down vblank interrupts
*/
spin_lock_irq(&dev->event_lock);
spin_lock(&dev->vbl_lock);
drm_dbg_vbl(dev, "crtc %d, vblank enabled %d, inmodeset %d\n",
pipe, vblank->enabled, vblank->inmodeset);
/* Avoid redundant vblank disables without previous
* drm_crtc_vblank_on(). */
if (drm_core_check_feature(dev, DRIVER_ATOMIC) || !vblank->inmodeset)
drm_vblank_disable_and_save(dev, pipe);
wake_up(&vblank->queue);
/*
* Prevent subsequent drm_vblank_get() from re-enabling
* the vblank interrupt by bumping the refcount.
*/
if (!vblank->inmodeset) {
atomic_inc(&vblank->refcount);
vblank->inmodeset = 1;
}
spin_unlock(&dev->vbl_lock);
/* Send any queued vblank events, lest the natives grow disquiet */
seq = drm_vblank_count_and_time(dev, pipe, &now);
list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
if (e->pipe != pipe)
continue;
drm_dbg_core(dev, "Sending premature vblank event on disable: "
"wanted %llu, current %llu\n",
e->sequence, seq);
list_del(&e->base.link);
drm_vblank_put(dev, pipe);
send_vblank_event(dev, e, seq, now);
}
/* Cancel any leftover pending vblank work */
drm_vblank_cancel_pending_works(vblank);
spin_unlock_irq(&dev->event_lock);
/* Will be reset by the modeset helpers when re-enabling the crtc by
* calling drm_calc_timestamping_constants(). */
vblank->hwmode.crtc_clock = 0;
/* Wait for any vblank work that's still executing to finish */
drm_vblank_flush_worker(vblank);
}
EXPORT_SYMBOL(drm_crtc_vblank_off);
/**
* drm_crtc_vblank_reset - reset vblank state to off on a CRTC
* @crtc: CRTC in question
*
* Drivers can use this function to reset the vblank state to off at load time.
* Drivers should use this together with the drm_crtc_vblank_off() and
* drm_crtc_vblank_on() functions. The difference compared to
* drm_crtc_vblank_off() is that this function doesn't save the vblank counter
* and hence doesn't need to call any driver hooks.
*
* This is useful for recovering driver state e.g. on driver load, or on resume.
*/
void drm_crtc_vblank_reset(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
spin_lock_irq(&dev->vbl_lock);
/*
* Prevent subsequent drm_vblank_get() from enabling the vblank
* interrupt by bumping the refcount.
*/
if (!vblank->inmodeset) {
atomic_inc(&vblank->refcount);
vblank->inmodeset = 1;
}
spin_unlock_irq(&dev->vbl_lock);
drm_WARN_ON(dev, !list_empty(&dev->vblank_event_list));
drm_WARN_ON(dev, !list_empty(&vblank->pending_work));
}
EXPORT_SYMBOL(drm_crtc_vblank_reset);
/**
* drm_crtc_set_max_vblank_count - configure the hw max vblank counter value
* @crtc: CRTC in question
* @max_vblank_count: max hardware vblank counter value
*
* Update the maximum hardware vblank counter value for @crtc
* at runtime. Useful for hardware where the operation of the
* hardware vblank counter depends on the currently active
* display configuration.
*
* For example, if the hardware vblank counter does not work
* when a specific connector is active the maximum can be set
* to zero. And when that specific connector isn't active the
* maximum can again be set to the appropriate non-zero value.
*
* If used, must be called before drm_vblank_on().
*/
void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc,
u32 max_vblank_count)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
drm_WARN_ON(dev, dev->max_vblank_count);
drm_WARN_ON(dev, !READ_ONCE(vblank->inmodeset));
vblank->max_vblank_count = max_vblank_count;
}
EXPORT_SYMBOL(drm_crtc_set_max_vblank_count);
/**
* drm_crtc_vblank_on - enable vblank events on a CRTC
* @crtc: CRTC in question
*
* This functions restores the vblank interrupt state captured with
* drm_crtc_vblank_off() again and is generally called when enabling @crtc. Note
* that calls to drm_crtc_vblank_on() and drm_crtc_vblank_off() can be
* unbalanced and so can also be unconditionally called in driver load code to
* reflect the current hardware state of the crtc.
*/
void drm_crtc_vblank_on(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
spin_lock_irq(&dev->vbl_lock);
drm_dbg_vbl(dev, "crtc %d, vblank enabled %d, inmodeset %d\n",
pipe, vblank->enabled, vblank->inmodeset);
/* Drop our private "prevent drm_vblank_get" refcount */
if (vblank->inmodeset) {
atomic_dec(&vblank->refcount);
vblank->inmodeset = 0;
}
drm_reset_vblank_timestamp(dev, pipe);
/*
* re-enable interrupts if there are users left, or the
* user wishes vblank interrupts to be enabled all the time.
*/
if (atomic_read(&vblank->refcount) != 0 || drm_vblank_offdelay == 0)
drm_WARN_ON(dev, drm_vblank_enable(dev, pipe));
spin_unlock_irq(&dev->vbl_lock);
}
EXPORT_SYMBOL(drm_crtc_vblank_on);
/**
* drm_vblank_restore - estimate missed vblanks and update vblank count.
* @dev: DRM device
* @pipe: CRTC index
*
* Power manamement features can cause frame counter resets between vblank
* disable and enable. Drivers can use this function in their
* &drm_crtc_funcs.enable_vblank implementation to estimate missed vblanks since
* the last &drm_crtc_funcs.disable_vblank using timestamps and update the
* vblank counter.
*
* This function is the legacy version of drm_crtc_vblank_restore().
*/
void drm_vblank_restore(struct drm_device *dev, unsigned int pipe)
{
ktime_t t_vblank;
struct drm_vblank_crtc *vblank;
int framedur_ns;
u64 diff_ns;
u32 cur_vblank, diff = 1;
int count = DRM_TIMESTAMP_MAXRETRIES;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
assert_spin_locked(&dev->vbl_lock);
assert_spin_locked(&dev->vblank_time_lock);
vblank = &dev->vblank[pipe];
drm_WARN_ONCE(dev,
drm_debug_enabled(DRM_UT_VBL) && !vblank->framedur_ns,
"Cannot compute missed vblanks without frame duration\n");
framedur_ns = vblank->framedur_ns;
do {
cur_vblank = __get_vblank_counter(dev, pipe);
drm_get_last_vbltimestamp(dev, pipe, &t_vblank, false);
} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time));
if (framedur_ns)
diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
drm_dbg_vbl(dev,
"missed %d vblanks in %lld ns, frame duration=%d ns, hw_diff=%d\n",
diff, diff_ns, framedur_ns, cur_vblank - vblank->last);
store_vblank(dev, pipe, diff, t_vblank, cur_vblank);
}
EXPORT_SYMBOL(drm_vblank_restore);
/**
* drm_crtc_vblank_restore - estimate missed vblanks and update vblank count.
* @crtc: CRTC in question
*
* Power manamement features can cause frame counter resets between vblank
* disable and enable. Drivers can use this function in their
* &drm_crtc_funcs.enable_vblank implementation to estimate missed vblanks since
* the last &drm_crtc_funcs.disable_vblank using timestamps and update the
* vblank counter.
*/
void drm_crtc_vblank_restore(struct drm_crtc *crtc)
{
drm_vblank_restore(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_restore);
static void drm_legacy_vblank_pre_modeset(struct drm_device *dev,
unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
/* vblank is not initialized (IRQ not installed ?), or has been freed */
if (!drm_dev_has_vblank(dev))
return;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
/*
* To avoid all the problems that might happen if interrupts
* were enabled/disabled around or between these calls, we just
* have the kernel take a reference on the CRTC (just once though
* to avoid corrupting the count if multiple, mismatch calls occur),
* so that interrupts remain enabled in the interim.
*/
if (!vblank->inmodeset) {
vblank->inmodeset = 0x1;
if (drm_vblank_get(dev, pipe) == 0)
vblank->inmodeset |= 0x2;
}
}
static void drm_legacy_vblank_post_modeset(struct drm_device *dev,
unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
/* vblank is not initialized (IRQ not installed ?), or has been freed */
if (!drm_dev_has_vblank(dev))
return;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return;
if (vblank->inmodeset) {
spin_lock_irq(&dev->vbl_lock);
drm_reset_vblank_timestamp(dev, pipe);
spin_unlock_irq(&dev->vbl_lock);
if (vblank->inmodeset & 0x2)
drm_vblank_put(dev, pipe);
vblank->inmodeset = 0;
}
}
int drm_legacy_modeset_ctl_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_modeset_ctl *modeset = data;
unsigned int pipe;
/* If drm_vblank_init() hasn't been called yet, just no-op */
if (!drm_dev_has_vblank(dev))
return 0;
/* KMS drivers handle this internally */
if (!drm_core_check_feature(dev, DRIVER_LEGACY))
return 0;
pipe = modeset->crtc;
if (pipe >= dev->num_crtcs)
return -EINVAL;
switch (modeset->cmd) {
case _DRM_PRE_MODESET:
drm_legacy_vblank_pre_modeset(dev, pipe);
break;
case _DRM_POST_MODESET:
drm_legacy_vblank_post_modeset(dev, pipe);
break;
default:
return -EINVAL;
}
return 0;
}
static int drm_queue_vblank_event(struct drm_device *dev, unsigned int pipe,
u64 req_seq,
union drm_wait_vblank *vblwait,
struct drm_file *file_priv)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
struct drm_pending_vblank_event *e;
ktime_t now;
u64 seq;
int ret;
e = kzalloc(sizeof(*e), GFP_KERNEL);
if (e == NULL) {
ret = -ENOMEM;
goto err_put;
}
e->pipe = pipe;
e->event.base.type = DRM_EVENT_VBLANK;
e->event.base.length = sizeof(e->event.vbl);
e->event.vbl.user_data = vblwait->request.signal;
e->event.vbl.crtc_id = 0;
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
if (crtc)
e->event.vbl.crtc_id = crtc->base.id;
}
spin_lock_irq(&dev->event_lock);
/*
* drm_crtc_vblank_off() might have been called after we called
* drm_vblank_get(). drm_crtc_vblank_off() holds event_lock around the
* vblank disable, so no need for further locking. The reference from
* drm_vblank_get() protects against vblank disable from another source.
*/
if (!READ_ONCE(vblank->enabled)) {
ret = -EINVAL;
goto err_unlock;
}
ret = drm_event_reserve_init_locked(dev, file_priv, &e->base,
&e->event.base);
if (ret)
goto err_unlock;
seq = drm_vblank_count_and_time(dev, pipe, &now);
drm_dbg_core(dev, "event on vblank count %llu, current %llu, crtc %u\n",
req_seq, seq, pipe);
trace_drm_vblank_event_queued(file_priv, pipe, req_seq);
e->sequence = req_seq;
if (drm_vblank_passed(seq, req_seq)) {
drm_vblank_put(dev, pipe);
send_vblank_event(dev, e, seq, now);
vblwait->reply.sequence = seq;
} else {
/* drm_handle_vblank_events will call drm_vblank_put */
list_add_tail(&e->base.link, &dev->vblank_event_list);
vblwait->reply.sequence = req_seq;
}
spin_unlock_irq(&dev->event_lock);
return 0;
err_unlock:
spin_unlock_irq(&dev->event_lock);
kfree(e);
err_put:
drm_vblank_put(dev, pipe);
return ret;
}
static bool drm_wait_vblank_is_query(union drm_wait_vblank *vblwait)
{
if (vblwait->request.sequence)
return false;
return _DRM_VBLANK_RELATIVE ==
(vblwait->request.type & (_DRM_VBLANK_TYPES_MASK |
_DRM_VBLANK_EVENT |
_DRM_VBLANK_NEXTONMISS));
}
/*
* Widen a 32-bit param to 64-bits.
*
* \param narrow 32-bit value (missing upper 32 bits)
* \param near 64-bit value that should be 'close' to near
*
* This function returns a 64-bit value using the lower 32-bits from
* 'narrow' and constructing the upper 32-bits so that the result is
* as close as possible to 'near'.
*/
static u64 widen_32_to_64(u32 narrow, u64 near)
{
return near + (s32) (narrow - near);
}
static void drm_wait_vblank_reply(struct drm_device *dev, unsigned int pipe,
struct drm_wait_vblank_reply *reply)
{
ktime_t now;
struct timespec64 ts;
/*
* drm_wait_vblank_reply is a UAPI structure that uses 'long'
* to store the seconds. This is safe as we always use monotonic
* timestamps since linux-4.15.
*/
reply->sequence = drm_vblank_count_and_time(dev, pipe, &now);
ts = ktime_to_timespec64(now);
reply->tval_sec = (u32)ts.tv_sec;
reply->tval_usec = ts.tv_nsec / 1000;
}
int drm_wait_vblank_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_crtc *crtc;
struct drm_vblank_crtc *vblank;
union drm_wait_vblank *vblwait = data;
int ret;
u64 req_seq, seq;
unsigned int pipe_index;
unsigned int flags, pipe, high_pipe;
if (!dev->irq_enabled)
return -EOPNOTSUPP;
if (vblwait->request.type & _DRM_VBLANK_SIGNAL)
return -EINVAL;
if (vblwait->request.type &
~(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
_DRM_VBLANK_HIGH_CRTC_MASK)) {
drm_dbg_core(dev,
"Unsupported type value 0x%x, supported mask 0x%x\n",
vblwait->request.type,
(_DRM_VBLANK_TYPES_MASK | _DRM_VBLANK_FLAGS_MASK |
_DRM_VBLANK_HIGH_CRTC_MASK));
return -EINVAL;
}
flags = vblwait->request.type & _DRM_VBLANK_FLAGS_MASK;
high_pipe = (vblwait->request.type & _DRM_VBLANK_HIGH_CRTC_MASK);
if (high_pipe)
pipe_index = high_pipe >> _DRM_VBLANK_HIGH_CRTC_SHIFT;
else
pipe_index = flags & _DRM_VBLANK_SECONDARY ? 1 : 0;
/* Convert lease-relative crtc index into global crtc index */
if (drm_core_check_feature(dev, DRIVER_MODESET)) {
pipe = 0;
drm_for_each_crtc(crtc, dev) {
if (drm_lease_held(file_priv, crtc->base.id)) {
if (pipe_index == 0)
break;
pipe_index--;
}
pipe++;
}
} else {
pipe = pipe_index;
}
if (pipe >= dev->num_crtcs)
return -EINVAL;
vblank = &dev->vblank[pipe];
/* If the counter is currently enabled and accurate, short-circuit
* queries to return the cached timestamp of the last vblank.
*/
if (dev->vblank_disable_immediate &&
drm_wait_vblank_is_query(vblwait) &&
READ_ONCE(vblank->enabled)) {
drm_wait_vblank_reply(dev, pipe, &vblwait->reply);
return 0;
}
ret = drm_vblank_get(dev, pipe);
if (ret) {
drm_dbg_core(dev,
"crtc %d failed to acquire vblank counter, %d\n",
pipe, ret);
return ret;
}
seq = drm_vblank_count(dev, pipe);
switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) {
case _DRM_VBLANK_RELATIVE:
req_seq = seq + vblwait->request.sequence;
vblwait->request.sequence = req_seq;
vblwait->request.type &= ~_DRM_VBLANK_RELATIVE;
break;
case _DRM_VBLANK_ABSOLUTE:
req_seq = widen_32_to_64(vblwait->request.sequence, seq);
break;
default:
ret = -EINVAL;
goto done;
}
if ((flags & _DRM_VBLANK_NEXTONMISS) &&
drm_vblank_passed(seq, req_seq)) {
req_seq = seq + 1;
vblwait->request.type &= ~_DRM_VBLANK_NEXTONMISS;
vblwait->request.sequence = req_seq;
}
if (flags & _DRM_VBLANK_EVENT) {
/* must hold on to the vblank ref until the event fires
* drm_vblank_put will be called asynchronously
*/
return drm_queue_vblank_event(dev, pipe, req_seq, vblwait, file_priv);
}
if (req_seq != seq) {
int wait;
drm_dbg_core(dev, "waiting on vblank count %llu, crtc %u\n",
req_seq, pipe);
wait = wait_event_interruptible_timeout(vblank->queue,
drm_vblank_passed(drm_vblank_count(dev, pipe), req_seq) ||
!READ_ONCE(vblank->enabled),
msecs_to_jiffies(3000));
switch (wait) {
case 0:
/* timeout */
ret = -EBUSY;
break;
case -ERESTARTSYS:
/* interrupted by signal */
ret = -EINTR;
break;
default:
ret = 0;
break;
}
}
if (ret != -EINTR) {
drm_wait_vblank_reply(dev, pipe, &vblwait->reply);
drm_dbg_core(dev, "crtc %d returning %u to client\n",
pipe, vblwait->reply.sequence);
} else {
drm_dbg_core(dev, "crtc %d vblank wait interrupted by signal\n",
pipe);
}
done:
drm_vblank_put(dev, pipe);
return ret;
}
static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
{
struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
bool high_prec = false;
struct drm_pending_vblank_event *e, *t;
ktime_t now;
u64 seq;
assert_spin_locked(&dev->event_lock);
seq = drm_vblank_count_and_time(dev, pipe, &now);
list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
if (e->pipe != pipe)
continue;
if (!drm_vblank_passed(seq, e->sequence))
continue;
drm_dbg_core(dev, "vblank event on %llu, current %llu\n",
e->sequence, seq);
list_del(&e->base.link);
drm_vblank_put(dev, pipe);
send_vblank_event(dev, e, seq, now);
}
if (crtc && crtc->funcs->get_vblank_timestamp)
high_prec = true;
trace_drm_vblank_event(pipe, seq, now, high_prec);
}
/**
* drm_handle_vblank - handle a vblank event
* @dev: DRM device
* @pipe: index of CRTC where this event occurred
*
* Drivers should call this routine in their vblank interrupt handlers to
* update the vblank counter and send any signals that may be pending.
*
* This is the legacy version of drm_crtc_handle_vblank().
*/
bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
bool disable_irq;
if (drm_WARN_ON_ONCE(dev, !drm_dev_has_vblank(dev)))
return false;
if (drm_WARN_ON(dev, pipe >= dev->num_crtcs))
return false;
spin_lock_irqsave(&dev->event_lock, irqflags);
/* Need timestamp lock to prevent concurrent execution with
* vblank enable/disable, as this would cause inconsistent
* or corrupted timestamps and vblank counts.
*/
spin_lock(&dev->vblank_time_lock);
/* Vblank irq handling disabled. Nothing to do. */
if (!vblank->enabled) {
spin_unlock(&dev->vblank_time_lock);
spin_unlock_irqrestore(&dev->event_lock, irqflags);
return false;
}
drm_update_vblank_count(dev, pipe, true);
spin_unlock(&dev->vblank_time_lock);
wake_up(&vblank->queue);
/* With instant-off, we defer disabling the interrupt until after
* we finish processing the following vblank after all events have
* been signaled. The disable has to be last (after
* drm_handle_vblank_events) so that the timestamp is always accurate.
*/
disable_irq = (dev->vblank_disable_immediate &&
drm_vblank_offdelay > 0 &&
!atomic_read(&vblank->refcount));
drm_handle_vblank_events(dev, pipe);
drm_handle_vblank_works(vblank);
spin_unlock_irqrestore(&dev->event_lock, irqflags);
if (disable_irq)
vblank_disable_fn(&vblank->disable_timer);
return true;
}
EXPORT_SYMBOL(drm_handle_vblank);
/**
* drm_crtc_handle_vblank - handle a vblank event
* @crtc: where this event occurred
*
* Drivers should call this routine in their vblank interrupt handlers to
* update the vblank counter and send any signals that may be pending.
*
* This is the native KMS version of drm_handle_vblank().
*
* Note that for a given vblank counter value drm_crtc_handle_vblank()
* and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
* provide a barrier: Any writes done before calling
* drm_crtc_handle_vblank() will be visible to callers of the later
* functions, iff the vblank count is the same or a later one.
*
* See also &drm_vblank_crtc.count.
*
* Returns:
* True if the event was successfully handled, false on failure.
*/
bool drm_crtc_handle_vblank(struct drm_crtc *crtc)
{
return drm_handle_vblank(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_handle_vblank);
/*
* Get crtc VBLANK count.
*
* \param dev DRM device
* \param data user arguement, pointing to a drm_crtc_get_sequence structure.
* \param file_priv drm file private for the user's open file descriptor
*/
int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_crtc *crtc;
struct drm_vblank_crtc *vblank;
int pipe;
struct drm_crtc_get_sequence *get_seq = data;
ktime_t now;
bool vblank_enabled;
int ret;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
if (!dev->irq_enabled)
return -EOPNOTSUPP;
crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id);
if (!crtc)
return -ENOENT;
pipe = drm_crtc_index(crtc);
vblank = &dev->vblank[pipe];
vblank_enabled = dev->vblank_disable_immediate && READ_ONCE(vblank->enabled);
if (!vblank_enabled) {
ret = drm_crtc_vblank_get(crtc);
if (ret) {
drm_dbg_core(dev,
"crtc %d failed to acquire vblank counter, %d\n",
pipe, ret);
return ret;
}
}
drm_modeset_lock(&crtc->mutex, NULL);
if (crtc->state)
get_seq->active = crtc->state->enable;
else
get_seq->active = crtc->enabled;
drm_modeset_unlock(&crtc->mutex);
get_seq->sequence = drm_vblank_count_and_time(dev, pipe, &now);
get_seq->sequence_ns = ktime_to_ns(now);
if (!vblank_enabled)
drm_crtc_vblank_put(crtc);
return 0;
}
/*
* Queue a event for VBLANK sequence
*
* \param dev DRM device
* \param data user arguement, pointing to a drm_crtc_queue_sequence structure.
* \param file_priv drm file private for the user's open file descriptor
*/
int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
struct drm_crtc *crtc;
struct drm_vblank_crtc *vblank;
int pipe;
struct drm_crtc_queue_sequence *queue_seq = data;
ktime_t now;
struct drm_pending_vblank_event *e;
u32 flags;
u64 seq;
u64 req_seq;
int ret;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return -EOPNOTSUPP;
if (!dev->irq_enabled)
return -EOPNOTSUPP;
crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id);
if (!crtc)
return -ENOENT;
flags = queue_seq->flags;
/* Check valid flag bits */
if (flags & ~(DRM_CRTC_SEQUENCE_RELATIVE|
DRM_CRTC_SEQUENCE_NEXT_ON_MISS))
return -EINVAL;
pipe = drm_crtc_index(crtc);
vblank = &dev->vblank[pipe];
e = kzalloc(sizeof(*e), GFP_KERNEL);
if (e == NULL)
return -ENOMEM;
ret = drm_crtc_vblank_get(crtc);
if (ret) {
drm_dbg_core(dev,
"crtc %d failed to acquire vblank counter, %d\n",
pipe, ret);
goto err_free;
}
seq = drm_vblank_count_and_time(dev, pipe, &now);
req_seq = queue_seq->sequence;
if (flags & DRM_CRTC_SEQUENCE_RELATIVE)
req_seq += seq;
if ((flags & DRM_CRTC_SEQUENCE_NEXT_ON_MISS) && drm_vblank_passed(seq, req_seq))
req_seq = seq + 1;
e->pipe = pipe;
e->event.base.type = DRM_EVENT_CRTC_SEQUENCE;
e->event.base.length = sizeof(e->event.seq);
e->event.seq.user_data = queue_seq->user_data;
spin_lock_irq(&dev->event_lock);
/*
* drm_crtc_vblank_off() might have been called after we called
* drm_crtc_vblank_get(). drm_crtc_vblank_off() holds event_lock around the
* vblank disable, so no need for further locking. The reference from
* drm_crtc_vblank_get() protects against vblank disable from another source.
*/
if (!READ_ONCE(vblank->enabled)) {
ret = -EINVAL;
goto err_unlock;
}
ret = drm_event_reserve_init_locked(dev, file_priv, &e->base,
&e->event.base);
if (ret)
goto err_unlock;
e->sequence = req_seq;
if (drm_vblank_passed(seq, req_seq)) {
drm_crtc_vblank_put(crtc);
send_vblank_event(dev, e, seq, now);
queue_seq->sequence = seq;
} else {
/* drm_handle_vblank_events will call drm_vblank_put */
list_add_tail(&e->base.link, &dev->vblank_event_list);
queue_seq->sequence = req_seq;
}
spin_unlock_irq(&dev->event_lock);
return 0;
err_unlock:
spin_unlock_irq(&dev->event_lock);
drm_crtc_vblank_put(crtc);
err_free:
kfree(e);
return ret;
}