| /* SPDX-License-Identifier: GPL-2.0 or MIT */ |
| #ifndef __DRM_PANIC_H__ |
| #define __DRM_PANIC_H__ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/iosys-map.h> |
| |
| #include <drm/drm_device.h> |
| #include <drm/drm_fourcc.h> |
| /* |
| * Copyright (c) 2024 Intel |
| */ |
| |
| /** |
| * struct drm_scanout_buffer - DRM scanout buffer |
| * |
| * This structure holds the information necessary for drm_panic to draw the |
| * panic screen, and display it. |
| */ |
| struct drm_scanout_buffer { |
| /** |
| * @format: |
| * |
| * drm format of the scanout buffer. |
| */ |
| const struct drm_format_info *format; |
| |
| /** |
| * @map: |
| * |
| * Virtual address of the scanout buffer, either in memory or iomem. |
| * The scanout buffer should be in linear format, and can be directly |
| * sent to the display hardware. Tearing is not an issue for the panic |
| * screen. |
| */ |
| struct iosys_map map[DRM_FORMAT_MAX_PLANES]; |
| |
| /** |
| * @width: Width of the scanout buffer, in pixels. |
| */ |
| unsigned int width; |
| |
| /** |
| * @height: Height of the scanout buffer, in pixels. |
| */ |
| unsigned int height; |
| |
| /** |
| * @pitch: Length in bytes between the start of two consecutive lines. |
| */ |
| unsigned int pitch[DRM_FORMAT_MAX_PLANES]; |
| |
| /** |
| * @set_pixel: Optional function, to set a pixel color on the |
| * framebuffer. It allows to handle special tiling format inside the |
| * driver. |
| */ |
| void (*set_pixel)(struct drm_scanout_buffer *sb, unsigned int x, |
| unsigned int y, u32 color); |
| |
| }; |
| |
| /** |
| * drm_panic_trylock - try to enter the panic printing critical section |
| * @dev: struct drm_device |
| * @flags: unsigned long irq flags you need to pass to the unlock() counterpart |
| * |
| * This function must be called by any panic printing code. The panic printing |
| * attempt must be aborted if the trylock fails. |
| * |
| * Panic printing code can make the following assumptions while holding the |
| * panic lock: |
| * |
| * - Anything protected by drm_panic_lock() and drm_panic_unlock() pairs is safe |
| * to access. |
| * |
| * - Furthermore the panic printing code only registers in drm_dev_unregister() |
| * and gets removed in drm_dev_unregister(). This allows the panic code to |
| * safely access any state which is invariant in between these two function |
| * calls, like the list of planes &drm_mode_config.plane_list or most of the |
| * struct drm_plane structure. |
| * |
| * Specifically thanks to the protection around plane updates in |
| * drm_atomic_helper_swap_state() the following additional guarantees hold: |
| * |
| * - It is safe to deference the drm_plane.state pointer. |
| * |
| * - Anything in struct drm_plane_state or the driver's subclass thereof which |
| * stays invariant after the atomic check code has finished is safe to access. |
| * Specifically this includes the reference counted pointers to framebuffer |
| * and buffer objects. |
| * |
| * - Anything set up by &drm_plane_helper_funcs.fb_prepare and cleaned up |
| * &drm_plane_helper_funcs.fb_cleanup is safe to access, as long as it stays |
| * invariant between these two calls. This also means that for drivers using |
| * dynamic buffer management the framebuffer is pinned, and therefer all |
| * relevant datastructures can be accessed without taking any further locks |
| * (which would be impossible in panic context anyway). |
| * |
| * - Importantly, software and hardware state set up by |
| * &drm_plane_helper_funcs.begin_fb_access and |
| * &drm_plane_helper_funcs.end_fb_access is not safe to access. |
| * |
| * Drivers must not make any assumptions about the actual state of the hardware, |
| * unless they explicitly protected these hardware access with drm_panic_lock() |
| * and drm_panic_unlock(). |
| * |
| * Return: |
| * %0 when failing to acquire the raw spinlock, nonzero on success. |
| */ |
| #define drm_panic_trylock(dev, flags) \ |
| raw_spin_trylock_irqsave(&(dev)->mode_config.panic_lock, flags) |
| |
| /** |
| * drm_panic_lock - protect panic printing relevant state |
| * @dev: struct drm_device |
| * @flags: unsigned long irq flags you need to pass to the unlock() counterpart |
| * |
| * This function must be called to protect software and hardware state that the |
| * panic printing code must be able to rely on. The protected sections must be |
| * as small as possible. It uses the irqsave/irqrestore variant, and can be |
| * called from irq handler. Examples include: |
| * |
| * - Access to peek/poke or other similar registers, if that is the way the |
| * driver prints the pixels into the scanout buffer at panic time. |
| * |
| * - Updates to pointers like &drm_plane.state, allowing the panic handler to |
| * safely deference these. This is done in drm_atomic_helper_swap_state(). |
| * |
| * - An state that isn't invariant and that the driver must be able to access |
| * during panic printing. |
| */ |
| |
| #define drm_panic_lock(dev, flags) \ |
| raw_spin_lock_irqsave(&(dev)->mode_config.panic_lock, flags) |
| |
| /** |
| * drm_panic_unlock - end of the panic printing critical section |
| * @dev: struct drm_device |
| * @flags: irq flags that were returned when acquiring the lock |
| * |
| * Unlocks the raw spinlock acquired by either drm_panic_lock() or |
| * drm_panic_trylock(). |
| */ |
| #define drm_panic_unlock(dev, flags) \ |
| raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags) |
| |
| #ifdef CONFIG_DRM_PANIC |
| |
| void drm_panic_register(struct drm_device *dev); |
| void drm_panic_unregister(struct drm_device *dev); |
| |
| #else |
| |
| static inline void drm_panic_register(struct drm_device *dev) {} |
| static inline void drm_panic_unregister(struct drm_device *dev) {} |
| |
| #endif |
| |
| #endif /* __DRM_PANIC_H__ */ |