drivers/gpu/drm/nouveau/nouveau_backlight.c - linux - Git at Google

 /*
  * Copyright (C) 2009 Red Hat <mjg@redhat.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 THE COPYRIGHT OWNER(S) 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.
  *
  */

 /*
  * Authors:
  *  Matthew Garrett <mjg@redhat.com>
  *
  * Register locations derived from NVClock by Roderick Colenbrander
  */

 #include <linux/apple-gmux.h>
 #include <linux/backlight.h>
 #include <linux/idr.h>

 #include "nouveau_drv.h"
 #include "nouveau_reg.h"
 #include "nouveau_encoder.h"
 #include "nouveau_connector.h"
 #include "nouveau_acpi.h"

 static struct ida bl_ida;
 #define BL_NAME_SIZE 15 // 12 for name + 2 for digits + 1 for '\0'

 static bool
 nouveau_get_backlight_name(char backlight_name[BL_NAME_SIZE],
 			   struct nouveau_backlight *bl)
 {
 	const int nb = ida_alloc_max(&bl_ida, 99, GFP_KERNEL);

 	if (nb < 0)
 		return false;
 	if (nb > 0)
 		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
 	else
 		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight");
 	bl->id = nb;
 	return true;
 }

 static int
 nv40_get_intensity(struct backlight_device *bd)
 {
 	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 	int val = (nvif_rd32(device, NV40_PMC_BACKLIGHT) &
 		   NV40_PMC_BACKLIGHT_MASK) >> 16;

 	return val;
 }

 static int
 nv40_set_intensity(struct backlight_device *bd)
 {
 	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 	int val = bd->props.brightness;
 	int reg = nvif_rd32(device, NV40_PMC_BACKLIGHT);

 	nvif_wr32(device, NV40_PMC_BACKLIGHT,
 		  (val << 16) | (reg & ~NV40_PMC_BACKLIGHT_MASK));

 	return 0;
 }

 static const struct backlight_ops nv40_bl_ops = {
 	.options = BL_CORE_SUSPENDRESUME,
 	.get_brightness = nv40_get_intensity,
 	.update_status = nv40_set_intensity,
 };

 static int
 nv40_backlight_init(struct nouveau_encoder *encoder,
 		    struct backlight_properties *props,
 		    const struct backlight_ops **ops)
 {
 	struct nouveau_drm *drm = nouveau_drm(encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;

 	if (!(nvif_rd32(device, NV40_PMC_BACKLIGHT) & NV40_PMC_BACKLIGHT_MASK))
 		return -ENODEV;

 	props->max_brightness = 31;
 	*ops = &nv40_bl_ops;
 	return 0;
 }

 static int
 nv50_get_intensity(struct backlight_device *bd)
 {
 	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 	int or = ffs(nv_encoder->dcb->or) - 1;
 	u32 div = 1025;
 	u32 val;

 	val  = nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(or));
 	val &= NV50_PDISP_SOR_PWM_CTL_VAL;
 	return ((val * 100) + (div / 2)) / div;
 }

 static int
 nv50_set_intensity(struct backlight_device *bd)
 {
 	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 	int or = ffs(nv_encoder->dcb->or) - 1;
 	u32 div = 1025;
 	u32 val = (bd->props.brightness * div) / 100;

 	nvif_wr32(device, NV50_PDISP_SOR_PWM_CTL(or),
 		  NV50_PDISP_SOR_PWM_CTL_NEW | val);
 	return 0;
 }

 static const struct backlight_ops nv50_bl_ops = {
 	.options = BL_CORE_SUSPENDRESUME,
 	.get_brightness = nv50_get_intensity,
 	.update_status = nv50_set_intensity,
 };

 /*
  * eDP brightness callbacks need to happen under lock, since we need to
  * enable/disable the backlight ourselves for modesets
  */
 static int
 nv50_edp_get_brightness(struct backlight_device *bd)
 {
 	struct drm_connector *connector = dev_get_drvdata(bd->dev.parent);
 	struct drm_device *dev = connector->dev;
 	struct drm_crtc *crtc;
 	struct drm_modeset_acquire_ctx ctx;
 	int ret = 0;

 	drm_modeset_acquire_init(&ctx, 0);

 retry:
 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
 	if (ret == -EDEADLK)
 		goto deadlock;
 	else if (ret < 0)
 		goto out;

 	crtc = connector->state->crtc;
 	if (!crtc)
 		goto out;

 	ret = drm_modeset_lock(&crtc->mutex, &ctx);
 	if (ret == -EDEADLK)
 		goto deadlock;
 	else if (ret < 0)
 		goto out;

 	if (!crtc->state->active)
 		goto out;

 	ret = bd->props.brightness;
 out:
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
 	return ret;
 deadlock:
 	drm_modeset_backoff(&ctx);
 	goto retry;
 }

 static int
 nv50_edp_set_brightness(struct backlight_device *bd)
 {
 	struct drm_connector *connector = dev_get_drvdata(bd->dev.parent);
 	struct nouveau_connector *nv_connector = nouveau_connector(connector);
 	struct drm_device *dev = connector->dev;
 	struct drm_crtc *crtc;
 	struct drm_dp_aux *aux = &nv_connector->aux;
 	struct nouveau_backlight *nv_bl = nv_connector->backlight;
 	struct drm_modeset_acquire_ctx ctx;
 	int ret = 0;

 	drm_modeset_acquire_init(&ctx, 0);
 retry:
 	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
 	if (ret == -EDEADLK)
 		goto deadlock;
 	else if (ret < 0)
 		goto out;

 	crtc = connector->state->crtc;
 	if (!crtc)
 		goto out;

 	ret = drm_modeset_lock(&crtc->mutex, &ctx);
 	if (ret == -EDEADLK)
 		goto deadlock;
 	else if (ret < 0)
 		goto out;

 	if (crtc->state->active)
 		ret = drm_edp_backlight_set_level(aux, &nv_bl->edp_info, bd->props.brightness);

 out:
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
 	return ret;
 deadlock:
 	drm_modeset_backoff(&ctx);
 	goto retry;
 }

 static const struct backlight_ops nv50_edp_bl_ops = {
 	.get_brightness = nv50_edp_get_brightness,
 	.update_status = nv50_edp_set_brightness,
 };

 static int
 nva3_get_intensity(struct backlight_device *bd)
 {
 	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 	int or = ffs(nv_encoder->dcb->or) - 1;
 	u32 div, val;

 	div  = nvif_rd32(device, NV50_PDISP_SOR_PWM_DIV(or));
 	val  = nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(or));
 	val &= NVA3_PDISP_SOR_PWM_CTL_VAL;
 	if (div && div >= val)
 		return ((val * 100) + (div / 2)) / div;

 	return 100;
 }

 static int
 nva3_set_intensity(struct backlight_device *bd)
 {
 	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 	int or = ffs(nv_encoder->dcb->or) - 1;
 	u32 div, val;

 	div = nvif_rd32(device, NV50_PDISP_SOR_PWM_DIV(or));

 	val = backlight_get_brightness(bd);
 	if (val)
 		val = (val * div) / 100;

 	if (div) {
 		nvif_wr32(device, NV50_PDISP_SOR_PWM_CTL(or),
 			  val |
 			  NV50_PDISP_SOR_PWM_CTL_NEW |
 			  NVA3_PDISP_SOR_PWM_CTL_UNK);
 		return 0;
 	}

 	return -EINVAL;
 }

 static const struct backlight_ops nva3_bl_ops = {
 	.options = BL_CORE_SUSPENDRESUME,
 	.get_brightness = nva3_get_intensity,
 	.update_status = nva3_set_intensity,
 };

 /* FIXME: perform backlight probing for eDP _before_ this, this only gets called after connector
  * registration which happens after the initial modeset
  */
 static int
 nv50_backlight_init(struct nouveau_backlight *bl,
 		    struct nouveau_connector *nv_conn,
 		    struct nouveau_encoder *nv_encoder,
 		    struct backlight_properties *props,
 		    const struct backlight_ops **ops)
 {
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;

 	if (!nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(ffs(nv_encoder->dcb->or) - 1)) ||
 	    nv_conn->base.status != connector_status_connected)
 		return -ENODEV;

 	if (nv_conn->type == DCB_CONNECTOR_eDP) {
 		int ret;
 		u16 current_level;
 		u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
 		u8 current_mode;

 		ret = drm_dp_dpcd_read(&nv_conn->aux, DP_EDP_DPCD_REV, edp_dpcd,
 				       EDP_DISPLAY_CTL_CAP_SIZE);
 		if (ret < 0)
 			return ret;

 		/* TODO: Add support for hybrid PWM/DPCD panels */
 		if (drm_edp_backlight_supported(edp_dpcd) &&
 		    (edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
 		    (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
 			NV_DEBUG(drm, "DPCD backlight controls supported on %s\n",
 				 nv_conn->base.name);

 			ret = drm_edp_backlight_init(&nv_conn->aux, &bl->edp_info, 0, edp_dpcd,
 						     &current_level, &current_mode);
 			if (ret < 0)
 				return ret;

 			ret = drm_edp_backlight_enable(&nv_conn->aux, &bl->edp_info, current_level);
 			if (ret < 0) {
 				NV_ERROR(drm, "Failed to enable backlight on %s: %d\n",
 					 nv_conn->base.name, ret);
 				return ret;
 			}

 			*ops = &nv50_edp_bl_ops;
 			props->brightness = current_level;
 			props->max_brightness = bl->edp_info.max;
 			bl->uses_dpcd = true;
 			return 0;
 		}
 	}

 	if (drm->client.device.info.chipset <= 0xa0 ||
 	    drm->client.device.info.chipset == 0xaa ||
 	    drm->client.device.info.chipset == 0xac)
 		*ops = &nv50_bl_ops;
 	else
 		*ops = &nva3_bl_ops;

 	props->max_brightness = 100;

 	return 0;
 }

 int
 nouveau_backlight_init(struct drm_connector *connector)
 {
 	struct nouveau_drm *drm = nouveau_drm(connector->dev);
 	struct nouveau_backlight *bl;
 	struct nouveau_encoder *nv_encoder = NULL;
 	struct nvif_device *device = &drm->client.device;
 	char backlight_name[BL_NAME_SIZE];
 	struct backlight_properties props = {0};
 	const struct backlight_ops *ops;
 	int ret;

 	if (apple_gmux_present()) {
 		NV_INFO_ONCE(drm, "Apple GMUX detected: not registering Nouveau backlight interface\n");
 		return 0;
 	}

 	if (connector->connector_type == DRM_MODE_CONNECTOR_LVDS)
 		nv_encoder = find_encoder(connector, DCB_OUTPUT_LVDS);
 	else if (connector->connector_type == DRM_MODE_CONNECTOR_eDP)
 		nv_encoder = find_encoder(connector, DCB_OUTPUT_DP);
 	else
 		return 0;

 	if (!nv_encoder)
 		return 0;

 	bl = kzalloc(sizeof(*bl), GFP_KERNEL);
 	if (!bl)
 		return -ENOMEM;

 	switch (device->info.family) {
 	case NV_DEVICE_INFO_V0_CURIE:
 		ret = nv40_backlight_init(nv_encoder, &props, &ops);
 		break;
 	case NV_DEVICE_INFO_V0_TESLA:
 	case NV_DEVICE_INFO_V0_FERMI:
 	case NV_DEVICE_INFO_V0_KEPLER:
 	case NV_DEVICE_INFO_V0_MAXWELL:
 	case NV_DEVICE_INFO_V0_PASCAL:
 	case NV_DEVICE_INFO_V0_VOLTA:
 	case NV_DEVICE_INFO_V0_TURING:
 	case NV_DEVICE_INFO_V0_AMPERE: //XXX: not confirmed
 		ret = nv50_backlight_init(bl, nouveau_connector(connector),
 					  nv_encoder, &props, &ops);
 		break;
 	default:
 		ret = 0;
 		goto fail_alloc;
 	}

 	if (ret) {
 		if (ret == -ENODEV)
 			ret = 0;
 		goto fail_alloc;
 	}

 	if (!nouveau_acpi_video_backlight_use_native()) {
 		NV_INFO(drm, "Skipping nv_backlight registration\n");
 		goto fail_alloc;
 	}

 	if (!nouveau_get_backlight_name(backlight_name, bl)) {
 		NV_ERROR(drm, "Failed to retrieve a unique name for the backlight interface\n");
 		goto fail_alloc;
 	}

 	props.type = BACKLIGHT_RAW;
 	bl->dev = backlight_device_register(backlight_name, connector->kdev,
 					    nv_encoder, ops, &props);
 	if (IS_ERR(bl->dev)) {
 		if (bl->id >= 0)
 			ida_free(&bl_ida, bl->id);
 		ret = PTR_ERR(bl->dev);
 		goto fail_alloc;
 	}

 	nouveau_connector(connector)->backlight = bl;
 	if (!bl->dev->props.brightness)
 		bl->dev->props.brightness =
 			bl->dev->ops->get_brightness(bl->dev);
 	backlight_update_status(bl->dev);

 	return 0;

 fail_alloc:
 	kfree(bl);
 	/*
 	 * If we get here we have an internal panel, but no nv_backlight,
 	 * try registering an ACPI video backlight device instead.
 	 */
 	if (ret == 0)
 		nouveau_acpi_video_register_backlight();

 	return ret;
 }

 void
 nouveau_backlight_fini(struct drm_connector *connector)
 {
 	struct nouveau_connector *nv_conn = nouveau_connector(connector);
 	struct nouveau_backlight *bl = nv_conn->backlight;

 	if (!bl)
 		return;

 	if (bl->id >= 0)
 		ida_free(&bl_ida, bl->id);

 	backlight_device_unregister(bl->dev);
 	nv_conn->backlight = NULL;
 	kfree(bl);
 }

 void
 nouveau_backlight_ctor(void)
 {
 	ida_init(&bl_ida);
 }

 void
 nouveau_backlight_dtor(void)
 {
 	ida_destroy(&bl_ida);
 }
	/*
	* Copyright (C) 2009 Red Hat <mjg@redhat.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 THE COPYRIGHT OWNER(S) 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.
	*
	*/

	/*
	* Authors:
	* Matthew Garrett <mjg@redhat.com>
	*
	* Register locations derived from NVClock by Roderick Colenbrander
	*/

	#include <linux/apple-gmux.h>
	#include <linux/backlight.h>
	#include <linux/idr.h>

	#include "nouveau_drv.h"
	#include "nouveau_reg.h"
	#include "nouveau_encoder.h"
	#include "nouveau_connector.h"
	#include "nouveau_acpi.h"

	static struct ida bl_ida;
	#define BL_NAME_SIZE 15 // 12 for name + 2 for digits + 1 for '\0'

	static bool
	nouveau_get_backlight_name(char backlight_name[BL_NAME_SIZE],
	struct nouveau_backlight *bl)
	{
	const int nb = ida_alloc_max(&bl_ida, 99, GFP_KERNEL);

	if (nb < 0)
	return false;
	if (nb > 0)
	snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
	else
	snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight");
	bl->id = nb;
	return true;
	}

	static int
	nv40_get_intensity(struct backlight_device *bd)
	{
	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;
	int val = (nvif_rd32(device, NV40_PMC_BACKLIGHT) &
	NV40_PMC_BACKLIGHT_MASK) >> 16;

	return val;
	}

	static int
	nv40_set_intensity(struct backlight_device *bd)
	{
	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;
	int val = bd->props.brightness;
	int reg = nvif_rd32(device, NV40_PMC_BACKLIGHT);

	nvif_wr32(device, NV40_PMC_BACKLIGHT,
	(val << 16) \| (reg & ~NV40_PMC_BACKLIGHT_MASK));

	return 0;
	}

	static const struct backlight_ops nv40_bl_ops = {
	.options = BL_CORE_SUSPENDRESUME,
	.get_brightness = nv40_get_intensity,
	.update_status = nv40_set_intensity,
	};

	static int
	nv40_backlight_init(struct nouveau_encoder *encoder,
	struct backlight_properties *props,
	const struct backlight_ops **ops)
	{
	struct nouveau_drm *drm = nouveau_drm(encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;

	if (!(nvif_rd32(device, NV40_PMC_BACKLIGHT) & NV40_PMC_BACKLIGHT_MASK))
	return -ENODEV;

	props->max_brightness = 31;
	*ops = &nv40_bl_ops;
	return 0;
	}

	static int
	nv50_get_intensity(struct backlight_device *bd)
	{
	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;
	int or = ffs(nv_encoder->dcb->or) - 1;
	u32 div = 1025;
	u32 val;

	val = nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(or));
	val &= NV50_PDISP_SOR_PWM_CTL_VAL;
	return ((val * 100) + (div / 2)) / div;
	}

	static int
	nv50_set_intensity(struct backlight_device *bd)
	{
	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;
	int or = ffs(nv_encoder->dcb->or) - 1;
	u32 div = 1025;
	u32 val = (bd->props.brightness * div) / 100;

	nvif_wr32(device, NV50_PDISP_SOR_PWM_CTL(or),
	NV50_PDISP_SOR_PWM_CTL_NEW \| val);
	return 0;
	}

	static const struct backlight_ops nv50_bl_ops = {
	.options = BL_CORE_SUSPENDRESUME,
	.get_brightness = nv50_get_intensity,
	.update_status = nv50_set_intensity,
	};

	/*
	* eDP brightness callbacks need to happen under lock, since we need to
	* enable/disable the backlight ourselves for modesets
	*/
	static int
	nv50_edp_get_brightness(struct backlight_device *bd)
	{
	struct drm_connector *connector = dev_get_drvdata(bd->dev.parent);
	struct drm_device *dev = connector->dev;
	struct drm_crtc *crtc;
	struct drm_modeset_acquire_ctx ctx;
	int ret = 0;

	drm_modeset_acquire_init(&ctx, 0);

	retry:
	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
	if (ret == -EDEADLK)
	goto deadlock;
	else if (ret < 0)
	goto out;

	crtc = connector->state->crtc;
	if (!crtc)
	goto out;

	ret = drm_modeset_lock(&crtc->mutex, &ctx);
	if (ret == -EDEADLK)
	goto deadlock;
	else if (ret < 0)
	goto out;

	if (!crtc->state->active)
	goto out;

	ret = bd->props.brightness;
	out:
	drm_modeset_drop_locks(&ctx);
	drm_modeset_acquire_fini(&ctx);
	return ret;
	deadlock:
	drm_modeset_backoff(&ctx);
	goto retry;
	}

	static int
	nv50_edp_set_brightness(struct backlight_device *bd)
	{
	struct drm_connector *connector = dev_get_drvdata(bd->dev.parent);
	struct nouveau_connector *nv_connector = nouveau_connector(connector);
	struct drm_device *dev = connector->dev;
	struct drm_crtc *crtc;
	struct drm_dp_aux *aux = &nv_connector->aux;
	struct nouveau_backlight *nv_bl = nv_connector->backlight;
	struct drm_modeset_acquire_ctx ctx;
	int ret = 0;

	drm_modeset_acquire_init(&ctx, 0);
	retry:
	ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
	if (ret == -EDEADLK)
	goto deadlock;
	else if (ret < 0)
	goto out;

	crtc = connector->state->crtc;
	if (!crtc)
	goto out;

	ret = drm_modeset_lock(&crtc->mutex, &ctx);
	if (ret == -EDEADLK)
	goto deadlock;
	else if (ret < 0)
	goto out;

	if (crtc->state->active)
	ret = drm_edp_backlight_set_level(aux, &nv_bl->edp_info, bd->props.brightness);

	out:
	drm_modeset_drop_locks(&ctx);
	drm_modeset_acquire_fini(&ctx);
	return ret;
	deadlock:
	drm_modeset_backoff(&ctx);
	goto retry;
	}

	static const struct backlight_ops nv50_edp_bl_ops = {
	.get_brightness = nv50_edp_get_brightness,
	.update_status = nv50_edp_set_brightness,
	};

	static int
	nva3_get_intensity(struct backlight_device *bd)
	{
	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;
	int or = ffs(nv_encoder->dcb->or) - 1;
	u32 div, val;

	div = nvif_rd32(device, NV50_PDISP_SOR_PWM_DIV(or));
	val = nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(or));
	val &= NVA3_PDISP_SOR_PWM_CTL_VAL;
	if (div && div >= val)
	return ((val * 100) + (div / 2)) / div;

	return 100;
	}

	static int
	nva3_set_intensity(struct backlight_device *bd)
	{
	struct nouveau_encoder *nv_encoder = bl_get_data(bd);
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;
	int or = ffs(nv_encoder->dcb->or) - 1;
	u32 div, val;

	div = nvif_rd32(device, NV50_PDISP_SOR_PWM_DIV(or));

	val = backlight_get_brightness(bd);
	if (val)
	val = (val * div) / 100;

	if (div) {
	nvif_wr32(device, NV50_PDISP_SOR_PWM_CTL(or),
	val \|
	NV50_PDISP_SOR_PWM_CTL_NEW \|
	NVA3_PDISP_SOR_PWM_CTL_UNK);
	return 0;
	}

	return -EINVAL;
	}

	static const struct backlight_ops nva3_bl_ops = {
	.options = BL_CORE_SUSPENDRESUME,
	.get_brightness = nva3_get_intensity,
	.update_status = nva3_set_intensity,
	};

	/* FIXME: perform backlight probing for eDP _before_ this, this only gets called after connector
	* registration which happens after the initial modeset
	*/
	static int
	nv50_backlight_init(struct nouveau_backlight *bl,
	struct nouveau_connector *nv_conn,
	struct nouveau_encoder *nv_encoder,
	struct backlight_properties *props,
	const struct backlight_ops **ops)
	{
	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
	struct nvif_object *device = &drm->client.device.object;

	if (!nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(ffs(nv_encoder->dcb->or) - 1)) \|\|
	nv_conn->base.status != connector_status_connected)
	return -ENODEV;

	if (nv_conn->type == DCB_CONNECTOR_eDP) {
	int ret;
	u16 current_level;
	u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
	u8 current_mode;

	ret = drm_dp_dpcd_read(&nv_conn->aux, DP_EDP_DPCD_REV, edp_dpcd,
	EDP_DISPLAY_CTL_CAP_SIZE);
	if (ret < 0)
	return ret;

	/* TODO: Add support for hybrid PWM/DPCD panels */
	if (drm_edp_backlight_supported(edp_dpcd) &&
	(edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
	(edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
	NV_DEBUG(drm, "DPCD backlight controls supported on %s\n",
	nv_conn->base.name);

	ret = drm_edp_backlight_init(&nv_conn->aux, &bl->edp_info, 0, edp_dpcd,
	&current_level, &current_mode);
	if (ret < 0)
	return ret;

	ret = drm_edp_backlight_enable(&nv_conn->aux, &bl->edp_info, current_level);
	if (ret < 0) {
	NV_ERROR(drm, "Failed to enable backlight on %s: %d\n",
	nv_conn->base.name, ret);
	return ret;
	}

	*ops = &nv50_edp_bl_ops;
	props->brightness = current_level;
	props->max_brightness = bl->edp_info.max;
	bl->uses_dpcd = true;
	return 0;
	}
	}

	if (drm->client.device.info.chipset <= 0xa0 \|\|
	drm->client.device.info.chipset == 0xaa \|\|
	drm->client.device.info.chipset == 0xac)
	*ops = &nv50_bl_ops;
	else
	*ops = &nva3_bl_ops;

	props->max_brightness = 100;

	return 0;
	}

	int
	nouveau_backlight_init(struct drm_connector *connector)
	{
	struct nouveau_drm *drm = nouveau_drm(connector->dev);
	struct nouveau_backlight *bl;
	struct nouveau_encoder *nv_encoder = NULL;
	struct nvif_device *device = &drm->client.device;
	char backlight_name[BL_NAME_SIZE];
	struct backlight_properties props = {0};
	const struct backlight_ops *ops;
	int ret;

	if (apple_gmux_present()) {
	NV_INFO_ONCE(drm, "Apple GMUX detected: not registering Nouveau backlight interface\n");
	return 0;
	}

	if (connector->connector_type == DRM_MODE_CONNECTOR_LVDS)
	nv_encoder = find_encoder(connector, DCB_OUTPUT_LVDS);
	else if (connector->connector_type == DRM_MODE_CONNECTOR_eDP)
	nv_encoder = find_encoder(connector, DCB_OUTPUT_DP);
	else
	return 0;

	if (!nv_encoder)
	return 0;

	bl = kzalloc(sizeof(*bl), GFP_KERNEL);
	if (!bl)
	return -ENOMEM;

	switch (device->info.family) {
	case NV_DEVICE_INFO_V0_CURIE:
	ret = nv40_backlight_init(nv_encoder, &props, &ops);
	break;
	case NV_DEVICE_INFO_V0_TESLA:
	case NV_DEVICE_INFO_V0_FERMI:
	case NV_DEVICE_INFO_V0_KEPLER:
	case NV_DEVICE_INFO_V0_MAXWELL:
	case NV_DEVICE_INFO_V0_PASCAL:
	case NV_DEVICE_INFO_V0_VOLTA:
	case NV_DEVICE_INFO_V0_TURING:
	case NV_DEVICE_INFO_V0_AMPERE: //XXX: not confirmed
	ret = nv50_backlight_init(bl, nouveau_connector(connector),
	nv_encoder, &props, &ops);
	break;
	default:
	ret = 0;
	goto fail_alloc;
	}

	if (ret) {
	if (ret == -ENODEV)
	ret = 0;
	goto fail_alloc;
	}

	if (!nouveau_acpi_video_backlight_use_native()) {
	NV_INFO(drm, "Skipping nv_backlight registration\n");
	goto fail_alloc;
	}

	if (!nouveau_get_backlight_name(backlight_name, bl)) {
	NV_ERROR(drm, "Failed to retrieve a unique name for the backlight interface\n");
	goto fail_alloc;
	}

	props.type = BACKLIGHT_RAW;
	bl->dev = backlight_device_register(backlight_name, connector->kdev,
	nv_encoder, ops, &props);
	if (IS_ERR(bl->dev)) {
	if (bl->id >= 0)
	ida_free(&bl_ida, bl->id);
	ret = PTR_ERR(bl->dev);
	goto fail_alloc;
	}

	nouveau_connector(connector)->backlight = bl;
	if (!bl->dev->props.brightness)
	bl->dev->props.brightness =
	bl->dev->ops->get_brightness(bl->dev);
	backlight_update_status(bl->dev);

	return 0;

	fail_alloc:
	kfree(bl);
	/*
	* If we get here we have an internal panel, but no nv_backlight,
	* try registering an ACPI video backlight device instead.
	*/
	if (ret == 0)
	nouveau_acpi_video_register_backlight();

	return ret;
	}

	void
	nouveau_backlight_fini(struct drm_connector *connector)
	{
	struct nouveau_connector *nv_conn = nouveau_connector(connector);
	struct nouveau_backlight *bl = nv_conn->backlight;

	if (!bl)
	return;

	if (bl->id >= 0)
	ida_free(&bl_ida, bl->id);

	backlight_device_unregister(bl->dev);
	nv_conn->backlight = NULL;
	kfree(bl);
	}

	void
	nouveau_backlight_ctor(void)
	{
	ida_init(&bl_ida);
	}

	void
	nouveau_backlight_dtor(void)
	{
	ida_destroy(&bl_ida);
	}