drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c - linux - Git at Google

 /*
  * Copyright © 2015 Intel Corporation
  *
  * 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 AUTHORS OR COPYRIGHT HOLDERS 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.
  *
  */

 /*
  * Laptops with Intel GPUs which have panels that support controlling the
  * backlight through DP AUX can actually use two different interfaces: Intel's
  * proprietary DP AUX backlight interface, and the standard VESA backlight
  * interface. Unfortunately, at the time of writing this a lot of laptops will
  * advertise support for the standard VESA backlight interface when they
  * don't properly support it. However, on these systems the Intel backlight
  * interface generally does work properly. Additionally, these systems will
  * usually just indicate that they use PWM backlight controls in their VBIOS
  * for some reason.
  */

 #include "i915_drv.h"
 #include "intel_backlight.h"
 #include "intel_display_types.h"
 #include "intel_dp.h"
 #include "intel_dp_aux_backlight.h"

 /* TODO:
  * Implement HDR, right now we just implement the bare minimum to bring us back into SDR mode so we
  * can make people's backlights work in the mean time
  */

 /*
  * DP AUX registers for Intel's proprietary HDR backlight interface. We define
  * them here since we'll likely be the only driver to ever use these.
  */
 #define INTEL_EDP_HDR_TCON_CAP0                                        0x340

 #define INTEL_EDP_HDR_TCON_CAP1                                        0x341
 # define INTEL_EDP_HDR_TCON_2084_DECODE_CAP                           BIT(0)
 # define INTEL_EDP_HDR_TCON_2020_GAMUT_CAP                            BIT(1)
 # define INTEL_EDP_HDR_TCON_TONE_MAPPING_CAP                          BIT(2)
 # define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_CAP                   BIT(3)
 # define INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP                       BIT(4)
 # define INTEL_EDP_HDR_TCON_OPTIMIZATION_CAP                          BIT(5)
 # define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP                       BIT(6)
 # define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_CONVERSION_CAP        BIT(7)

 #define INTEL_EDP_HDR_TCON_CAP2                                        0x342
 # define INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP                        BIT(0)

 #define INTEL_EDP_HDR_TCON_CAP3                                        0x343

 #define INTEL_EDP_HDR_GETSET_CTRL_PARAMS                               0x344
 # define INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE                        BIT(0)
 # define INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE                         BIT(1)
 # define INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE                       BIT(2) /* Pre-TGL+ */
 # define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE                BIT(3)
 # define INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE                     BIT(4)
 # define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_ENABLE                BIT(5)
 /* Bit 6 is reserved */
 # define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_ENABLE                    BIT(7)

 #define INTEL_EDP_HDR_CONTENT_LUMINANCE                                0x346 /* Pre-TGL+ */
 #define INTEL_EDP_HDR_PANEL_LUMINANCE_OVERRIDE                         0x34A
 #define INTEL_EDP_SDR_LUMINANCE_LEVEL                                  0x352
 #define INTEL_EDP_BRIGHTNESS_NITS_LSB                                  0x354
 #define INTEL_EDP_BRIGHTNESS_NITS_MSB                                  0x355
 #define INTEL_EDP_BRIGHTNESS_DELAY_FRAMES                              0x356
 #define INTEL_EDP_BRIGHTNESS_PER_FRAME_STEPS                           0x357

 #define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_0                            0x358
 # define INTEL_EDP_TCON_USAGE_MASK                             GENMASK(0, 3)
 # define INTEL_EDP_TCON_USAGE_UNKNOWN                                    0x0
 # define INTEL_EDP_TCON_USAGE_DESKTOP                                    0x1
 # define INTEL_EDP_TCON_USAGE_FULL_SCREEN_MEDIA                          0x2
 # define INTEL_EDP_TCON_USAGE_FULL_SCREEN_GAMING                         0x3
 # define INTEL_EDP_TCON_POWER_MASK                                    BIT(4)
 # define INTEL_EDP_TCON_POWER_DC                                    (0 << 4)
 # define INTEL_EDP_TCON_POWER_AC                                    (1 << 4)
 # define INTEL_EDP_TCON_OPTIMIZATION_STRENGTH_MASK             GENMASK(5, 7)

 #define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_1                            0x359

 enum intel_dp_aux_backlight_modparam {
 	INTEL_DP_AUX_BACKLIGHT_AUTO = -1,
 	INTEL_DP_AUX_BACKLIGHT_OFF = 0,
 	INTEL_DP_AUX_BACKLIGHT_ON = 1,
 	INTEL_DP_AUX_BACKLIGHT_FORCE_VESA = 2,
 	INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL = 3,
 };

 static bool is_intel_tcon_cap(const u8 tcon_cap[4])
 {
 	return tcon_cap[0] >= 1;
 }

 /* Intel EDP backlight callbacks */
 static bool
 intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
 {
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 	struct drm_dp_aux *aux = &intel_dp->aux;
 	struct intel_panel *panel = &connector->panel;
 	int ret;
 	u8 tcon_cap[4];

 	intel_dp_wait_source_oui(intel_dp);

 	ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
 	if (ret != sizeof(tcon_cap))
 		return false;

 	if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
 		return false;

 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Detected %s HDR backlight interface version %d\n",
 		    connector->base.base.id, connector->base.name,
 		    is_intel_tcon_cap(tcon_cap) ? "Intel" : "unsupported", tcon_cap[0]);

 	if (!is_intel_tcon_cap(tcon_cap))
 		return false;

 	/*
 	 * If we don't have HDR static metadata there is no way to
 	 * runtime detect used range for nits based control. For now
 	 * do not use Intel proprietary eDP backlight control if we
 	 * don't have this data in panel EDID. In case we find panel
 	 * which supports only nits based control, but doesn't provide
 	 * HDR static metadata we need to start maintaining table of
 	 * ranges for such panels.
 	 */
 	if (i915->display.params.enable_dpcd_backlight != INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL &&
 	    !(connector->base.hdr_sink_metadata.hdmi_type1.metadata_type &
 	      BIT(HDMI_STATIC_METADATA_TYPE1))) {
 		drm_info(&i915->drm,
 			 "[CONNECTOR:%d:%s] Panel is missing HDR static metadata. Possible support for Intel HDR backlight interface is not used. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=%d. needs this, please file a _new_ bug report on drm/i915, see " FDO_BUG_URL " for details.\n",
 			 connector->base.base.id, connector->base.name,
 			 INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL);
 		return false;
 	}

 	panel->backlight.edp.intel.sdr_uses_aux =
 		tcon_cap[2] & INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP;

 	return true;
 }

 static u32
 intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe)
 {
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	struct intel_panel *panel = &connector->panel;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 	u8 tmp;
 	u8 buf[2] = {};

 	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) != 1) {
 		drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read current backlight mode from DPCD\n",
 			connector->base.base.id, connector->base.name);
 		return 0;
 	}

 	if (!(tmp & INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE)) {
 		if (!panel->backlight.edp.intel.sdr_uses_aux) {
 			u32 pwm_level = panel->backlight.pwm_funcs->get(connector, pipe);

 			return intel_backlight_level_from_pwm(connector, pwm_level);
 		}

 		/* Assume 100% brightness if backlight controls aren't enabled yet */
 		return panel->backlight.max;
 	}

 	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
 			     sizeof(buf)) != sizeof(buf)) {
 		drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read brightness from DPCD\n",
 			connector->base.base.id, connector->base.name);
 		return 0;
 	}

 	return (buf[1] << 8 | buf[0]);
 }

 static void
 intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state, u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct drm_device *dev = connector->base.dev;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 	u8 buf[4] = {};

 	buf[0] = level & 0xFF;
 	buf[1] = (level & 0xFF00) >> 8;

 	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
 			      sizeof(buf)) != sizeof(buf))
 		drm_err(dev, "[CONNECTOR:%d:%s] Failed to write brightness level to DPCD\n",
 			connector->base.base.id, connector->base.name);
 }

 static void
 intel_dp_aux_hdr_set_backlight(const struct drm_connector_state *conn_state, u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct intel_panel *panel = &connector->panel;

 	if (panel->backlight.edp.intel.sdr_uses_aux) {
 		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
 	} else {
 		const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);

 		intel_backlight_set_pwm_level(conn_state, pwm_level);
 	}
 }

 static void
 intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
 				  const struct drm_connector_state *conn_state, u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct intel_panel *panel = &connector->panel;
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 	int ret;
 	u8 old_ctrl, ctrl;

 	intel_dp_wait_source_oui(intel_dp);

 	ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
 	if (ret != 1) {
 		drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read current backlight control mode: %d\n",
 			connector->base.base.id, connector->base.name, ret);
 		return;
 	}

 	ctrl = old_ctrl;
 	if (panel->backlight.edp.intel.sdr_uses_aux) {
 		ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
 		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
 	} else {
 		u32 pwm_level = intel_backlight_level_to_pwm(connector, level);

 		panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);

 		ctrl &= ~INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
 	}

 	if (ctrl != old_ctrl &&
 	    drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
 		drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to configure DPCD brightness controls\n",
 			connector->base.base.id, connector->base.name);
 }

 static void
 intel_dp_aux_hdr_disable_backlight(const struct drm_connector_state *conn_state, u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct intel_panel *panel = &connector->panel;

 	/* Nothing to do for AUX based backlight controls */
 	if (panel->backlight.edp.intel.sdr_uses_aux)
 		return;

 	/* Note we want the actual pwm_level to be 0, regardless of pwm_min */
 	panel->backlight.pwm_funcs->disable(conn_state, intel_backlight_invert_pwm_level(connector, 0));
 }

 static const char *dpcd_vs_pwm_str(bool aux)
 {
 	return aux ? "DPCD" : "PWM";
 }

 static int
 intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pipe)
 {
 	struct drm_i915_private *i915 = to_i915(connector->base.dev);
 	struct intel_panel *panel = &connector->panel;
 	struct drm_luminance_range_info *luminance_range =
 		&connector->base.display_info.luminance_range;
 	int ret;

 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] SDR backlight is controlled through %s\n",
 		    connector->base.base.id, connector->base.name,
 		    dpcd_vs_pwm_str(panel->backlight.edp.intel.sdr_uses_aux));

 	if (!panel->backlight.edp.intel.sdr_uses_aux) {
 		ret = panel->backlight.pwm_funcs->setup(connector, pipe);
 		if (ret < 0) {
 			drm_err(&i915->drm,
 				"[CONNECTOR:%d:%s] Failed to setup SDR backlight controls through PWM: %d\n",
 				connector->base.base.id, connector->base.name, ret);
 			return ret;
 		}
 	}

 	if (luminance_range->max_luminance) {
 		panel->backlight.max = luminance_range->max_luminance;
 		panel->backlight.min = luminance_range->min_luminance;
 	} else {
 		panel->backlight.max = 512;
 		panel->backlight.min = 0;
 	}

 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX HDR interface for backlight control (range %d..%d)\n",
 		    connector->base.base.id, connector->base.name,
 		    panel->backlight.min, panel->backlight.max);


 	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
 	panel->backlight.enabled = panel->backlight.level != 0;

 	return 0;
 }

 /* VESA backlight callbacks */
 static u32 intel_dp_aux_vesa_get_backlight(struct intel_connector *connector, enum pipe unused)
 {
 	return connector->panel.backlight.level;
 }

 static void
 intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state, u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct intel_panel *panel = &connector->panel;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

 	if (!panel->backlight.edp.vesa.info.aux_set) {
 		const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);

 		intel_backlight_set_pwm_level(conn_state, pwm_level);
 	}

 	drm_edp_backlight_set_level(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
 }

 static void
 intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 				   const struct drm_connector_state *conn_state, u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
 	struct intel_panel *panel = &connector->panel;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

 	if (!panel->backlight.edp.vesa.info.aux_enable) {
 		u32 pwm_level;

 		if (!panel->backlight.edp.vesa.info.aux_set)
 			pwm_level = intel_backlight_level_to_pwm(connector, level);
 		else
 			pwm_level = intel_backlight_invert_pwm_level(connector,
 								     panel->backlight.pwm_level_max);

 		panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
 	}

 	drm_edp_backlight_enable(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
 }

 static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state *old_conn_state,
 						u32 level)
 {
 	struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
 	struct intel_panel *panel = &connector->panel;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

 	drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.edp.vesa.info);

 	if (!panel->backlight.edp.vesa.info.aux_enable)
 		panel->backlight.pwm_funcs->disable(old_conn_state,
 						    intel_backlight_invert_pwm_level(connector, 0));
 }

 static int intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector, enum pipe pipe)
 {
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct intel_panel *panel = &connector->panel;
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	u16 current_level;
 	u8 current_mode;
 	int ret;

 	ret = drm_edp_backlight_init(&intel_dp->aux, &panel->backlight.edp.vesa.info,
 				     panel->vbt.backlight.pwm_freq_hz, intel_dp->edp_dpcd,
 				     &current_level, &current_mode);
 	if (ret < 0)
 		return ret;

 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX VESA backlight enable is controlled through %s\n",
 		    connector->base.base.id, connector->base.name,
 		    dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_enable));
 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX VESA backlight level is controlled through %s\n",
 		    connector->base.base.id, connector->base.name,
 		    dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_set));

 	if (!panel->backlight.edp.vesa.info.aux_set || !panel->backlight.edp.vesa.info.aux_enable) {
 		ret = panel->backlight.pwm_funcs->setup(connector, pipe);
 		if (ret < 0) {
 			drm_err(&i915->drm,
 				"[CONNECTOR:%d:%s] Failed to setup PWM backlight controls for eDP backlight: %d\n",
 				connector->base.base.id, connector->base.name, ret);
 			return ret;
 		}
 	}

 	if (panel->backlight.edp.vesa.info.aux_set) {
 		panel->backlight.max = panel->backlight.edp.vesa.info.max;
 		panel->backlight.min = 0;
 		if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
 			panel->backlight.level = current_level;
 			panel->backlight.enabled = panel->backlight.level != 0;
 		} else {
 			panel->backlight.level = panel->backlight.max;
 			panel->backlight.enabled = false;
 		}
 	} else {
 		panel->backlight.max = panel->backlight.pwm_level_max;
 		panel->backlight.min = panel->backlight.pwm_level_min;
 		if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_PWM) {
 			panel->backlight.level = panel->backlight.pwm_funcs->get(connector, pipe);
 			panel->backlight.enabled = panel->backlight.pwm_enabled;
 		} else {
 			panel->backlight.level = panel->backlight.max;
 			panel->backlight.enabled = false;
 		}
 	}

 	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX VESA interface for backlight control\n",
 		    connector->base.base.id, connector->base.name);

 	return 0;
 }

 static bool
 intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
 {
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);

 	if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
 		drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX Backlight Control Supported!\n",
 			    connector->base.base.id, connector->base.name);
 		return true;
 	}
 	return false;
 }

 static const struct intel_panel_bl_funcs intel_dp_hdr_bl_funcs = {
 	.setup = intel_dp_aux_hdr_setup_backlight,
 	.enable = intel_dp_aux_hdr_enable_backlight,
 	.disable = intel_dp_aux_hdr_disable_backlight,
 	.set = intel_dp_aux_hdr_set_backlight,
 	.get = intel_dp_aux_hdr_get_backlight,
 };

 static const struct intel_panel_bl_funcs intel_dp_vesa_bl_funcs = {
 	.setup = intel_dp_aux_vesa_setup_backlight,
 	.enable = intel_dp_aux_vesa_enable_backlight,
 	.disable = intel_dp_aux_vesa_disable_backlight,
 	.set = intel_dp_aux_vesa_set_backlight,
 	.get = intel_dp_aux_vesa_get_backlight,
 };

 int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
 {
 	struct drm_device *dev = connector->base.dev;
 	struct intel_panel *panel = &connector->panel;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 	bool try_intel_interface = false, try_vesa_interface = false;

 	/* Check the VBT and user's module parameters to figure out which
 	 * interfaces to probe
 	 */
 	switch (i915->display.params.enable_dpcd_backlight) {
 	case INTEL_DP_AUX_BACKLIGHT_OFF:
 		return -ENODEV;
 	case INTEL_DP_AUX_BACKLIGHT_AUTO:
 		switch (panel->vbt.backlight.type) {
 		case INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE:
 			try_vesa_interface = true;
 			break;
 		case INTEL_BACKLIGHT_DISPLAY_DDI:
 			try_intel_interface = true;
 			break;
 		default:
 			return -ENODEV;
 		}
 		break;
 	case INTEL_DP_AUX_BACKLIGHT_ON:
 		if (panel->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)
 			try_intel_interface = true;

 		try_vesa_interface = true;
 		break;
 	case INTEL_DP_AUX_BACKLIGHT_FORCE_VESA:
 		try_vesa_interface = true;
 		break;
 	case INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL:
 		try_intel_interface = true;
 		break;
 	}

 	/*
 	 * Since Intel has their own backlight control interface, the majority of machines out there
 	 * using DPCD backlight controls with Intel GPUs will be using this interface as opposed to
 	 * the VESA interface. However, other GPUs (such as Nvidia's) will always use the VESA
 	 * interface. This means that there's quite a number of panels out there that will advertise
 	 * support for both interfaces, primarily systems with Intel/Nvidia hybrid GPU setups.
 	 *
 	 * There's a catch to this though: on many panels that advertise support for both
 	 * interfaces, the VESA backlight interface will stop working once we've programmed the
 	 * panel with Intel's OUI - which is also required for us to be able to detect Intel's
 	 * backlight interface at all. This means that the only sensible way for us to detect both
 	 * interfaces is to probe for Intel's first, and VESA's second.
 	 */
 	if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector)) {
 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using Intel proprietary eDP backlight controls\n",
 			    connector->base.base.id, connector->base.name);
 		panel->backlight.funcs = &intel_dp_hdr_bl_funcs;
 		return 0;
 	}

 	if (try_vesa_interface && intel_dp_aux_supports_vesa_backlight(connector)) {
 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using VESA eDP backlight controls\n",
 			    connector->base.base.id, connector->base.name);
 		panel->backlight.funcs = &intel_dp_vesa_bl_funcs;
 		return 0;
 	}

 	return -ENODEV;
 }
	/*
	* Copyright © 2015 Intel Corporation
	*
	* 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 AUTHORS OR COPYRIGHT HOLDERS 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.
	*
	*/

	/*
	* Laptops with Intel GPUs which have panels that support controlling the
	* backlight through DP AUX can actually use two different interfaces: Intel's
	* proprietary DP AUX backlight interface, and the standard VESA backlight
	* interface. Unfortunately, at the time of writing this a lot of laptops will
	* advertise support for the standard VESA backlight interface when they
	* don't properly support it. However, on these systems the Intel backlight
	* interface generally does work properly. Additionally, these systems will
	* usually just indicate that they use PWM backlight controls in their VBIOS
	* for some reason.
	*/

	#include "i915_drv.h"
	#include "intel_backlight.h"
	#include "intel_display_types.h"
	#include "intel_dp.h"
	#include "intel_dp_aux_backlight.h"

	/* TODO:
	* Implement HDR, right now we just implement the bare minimum to bring us back into SDR mode so we
	* can make people's backlights work in the mean time
	*/

	/*
	* DP AUX registers for Intel's proprietary HDR backlight interface. We define
	* them here since we'll likely be the only driver to ever use these.
	*/
	#define INTEL_EDP_HDR_TCON_CAP0 0x340

	#define INTEL_EDP_HDR_TCON_CAP1 0x341
	# define INTEL_EDP_HDR_TCON_2084_DECODE_CAP BIT(0)
	# define INTEL_EDP_HDR_TCON_2020_GAMUT_CAP BIT(1)
	# define INTEL_EDP_HDR_TCON_TONE_MAPPING_CAP BIT(2)
	# define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_CAP BIT(3)
	# define INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP BIT(4)
	# define INTEL_EDP_HDR_TCON_OPTIMIZATION_CAP BIT(5)
	# define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP BIT(6)
	# define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_CONVERSION_CAP BIT(7)

	#define INTEL_EDP_HDR_TCON_CAP2 0x342
	# define INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP BIT(0)

	#define INTEL_EDP_HDR_TCON_CAP3 0x343

	#define INTEL_EDP_HDR_GETSET_CTRL_PARAMS 0x344
	# define INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE BIT(0)
	# define INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE BIT(1)
	# define INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE BIT(2) /* Pre-TGL+ */
	# define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE BIT(3)
	# define INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE BIT(4)
	# define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_ENABLE BIT(5)
	/* Bit 6 is reserved */
	# define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_ENABLE BIT(7)

	#define INTEL_EDP_HDR_CONTENT_LUMINANCE 0x346 /* Pre-TGL+ */
	#define INTEL_EDP_HDR_PANEL_LUMINANCE_OVERRIDE 0x34A
	#define INTEL_EDP_SDR_LUMINANCE_LEVEL 0x352
	#define INTEL_EDP_BRIGHTNESS_NITS_LSB 0x354
	#define INTEL_EDP_BRIGHTNESS_NITS_MSB 0x355
	#define INTEL_EDP_BRIGHTNESS_DELAY_FRAMES 0x356
	#define INTEL_EDP_BRIGHTNESS_PER_FRAME_STEPS 0x357

	#define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_0 0x358
	# define INTEL_EDP_TCON_USAGE_MASK GENMASK(0, 3)
	# define INTEL_EDP_TCON_USAGE_UNKNOWN 0x0
	# define INTEL_EDP_TCON_USAGE_DESKTOP 0x1
	# define INTEL_EDP_TCON_USAGE_FULL_SCREEN_MEDIA 0x2
	# define INTEL_EDP_TCON_USAGE_FULL_SCREEN_GAMING 0x3
	# define INTEL_EDP_TCON_POWER_MASK BIT(4)
	# define INTEL_EDP_TCON_POWER_DC (0 << 4)
	# define INTEL_EDP_TCON_POWER_AC (1 << 4)
	# define INTEL_EDP_TCON_OPTIMIZATION_STRENGTH_MASK GENMASK(5, 7)

	#define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_1 0x359

	enum intel_dp_aux_backlight_modparam {
	INTEL_DP_AUX_BACKLIGHT_AUTO = -1,
	INTEL_DP_AUX_BACKLIGHT_OFF = 0,
	INTEL_DP_AUX_BACKLIGHT_ON = 1,
	INTEL_DP_AUX_BACKLIGHT_FORCE_VESA = 2,
	INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL = 3,
	};

	static bool is_intel_tcon_cap(const u8 tcon_cap[4])
	{
	return tcon_cap[0] >= 1;
	}

	/* Intel EDP backlight callbacks */
	static bool
	intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
	{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
	struct drm_dp_aux *aux = &intel_dp->aux;
	struct intel_panel *panel = &connector->panel;
	int ret;
	u8 tcon_cap[4];

	intel_dp_wait_source_oui(intel_dp);

	ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
	if (ret != sizeof(tcon_cap))
	return false;

	if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
	return false;

	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Detected %s HDR backlight interface version %d\n",
	connector->base.base.id, connector->base.name,
	is_intel_tcon_cap(tcon_cap) ? "Intel" : "unsupported", tcon_cap[0]);

	if (!is_intel_tcon_cap(tcon_cap))
	return false;

	/*
	* If we don't have HDR static metadata there is no way to
	* runtime detect used range for nits based control. For now
	* do not use Intel proprietary eDP backlight control if we
	* don't have this data in panel EDID. In case we find panel
	* which supports only nits based control, but doesn't provide
	* HDR static metadata we need to start maintaining table of
	* ranges for such panels.
	*/
	if (i915->display.params.enable_dpcd_backlight != INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL &&
	!(connector->base.hdr_sink_metadata.hdmi_type1.metadata_type &
	BIT(HDMI_STATIC_METADATA_TYPE1))) {
	drm_info(&i915->drm,
	"[CONNECTOR:%d:%s] Panel is missing HDR static metadata. Possible support for Intel HDR backlight interface is not used. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=%d. needs this, please file a _new_ bug report on drm/i915, see " FDO_BUG_URL " for details.\n",
	connector->base.base.id, connector->base.name,
	INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL);
	return false;
	}

	panel->backlight.edp.intel.sdr_uses_aux =
	tcon_cap[2] & INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP;

	return true;
	}

	static u32
	intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe)
	{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
	u8 tmp;
	u8 buf[2] = {};

	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) != 1) {
	drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read current backlight mode from DPCD\n",
	connector->base.base.id, connector->base.name);
	return 0;
	}

	if (!(tmp & INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE)) {
	if (!panel->backlight.edp.intel.sdr_uses_aux) {
	u32 pwm_level = panel->backlight.pwm_funcs->get(connector, pipe);

	return intel_backlight_level_from_pwm(connector, pwm_level);
	}

	/* Assume 100% brightness if backlight controls aren't enabled yet */
	return panel->backlight.max;
	}

	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
	sizeof(buf)) != sizeof(buf)) {
	drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read brightness from DPCD\n",
	connector->base.base.id, connector->base.name);
	return 0;
	}

	return (buf[1] << 8 \| buf[0]);
	}

	static void
	intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state, u32 level)
	{
	struct intel_connector *connector = to_intel_connector(conn_state->connector);
	struct drm_device *dev = connector->base.dev;
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
	u8 buf[4] = {};

	buf[0] = level & 0xFF;
	buf[1] = (level & 0xFF00) >> 8;

	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
	sizeof(buf)) != sizeof(buf))
	drm_err(dev, "[CONNECTOR:%d:%s] Failed to write brightness level to DPCD\n",
	connector->base.base.id, connector->base.name);
	}

	static void
	intel_dp_aux_hdr_set_backlight(const struct drm_connector_state *conn_state, u32 level)
	{
	struct intel_connector *connector = to_intel_connector(conn_state->connector);
	struct intel_panel *panel = &connector->panel;

	if (panel->backlight.edp.intel.sdr_uses_aux) {
	intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
	} else {
	const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);

	intel_backlight_set_pwm_level(conn_state, pwm_level);
	}
	}

	static void
	intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
	const struct drm_connector_state *conn_state, u32 level)
	{
	struct intel_connector *connector = to_intel_connector(conn_state->connector);
	struct intel_panel *panel = &connector->panel;
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
	int ret;
	u8 old_ctrl, ctrl;

	intel_dp_wait_source_oui(intel_dp);

	ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
	if (ret != 1) {
	drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read current backlight control mode: %d\n",
	connector->base.base.id, connector->base.name, ret);
	return;
	}

	ctrl = old_ctrl;
	if (panel->backlight.edp.intel.sdr_uses_aux) {
	ctrl \|= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
	intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
	} else {
	u32 pwm_level = intel_backlight_level_to_pwm(connector, level);

	panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);

	ctrl &= ~INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
	}

	if (ctrl != old_ctrl &&
	drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
	drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to configure DPCD brightness controls\n",
	connector->base.base.id, connector->base.name);
	}

	static void
	intel_dp_aux_hdr_disable_backlight(const struct drm_connector_state *conn_state, u32 level)
	{
	struct intel_connector *connector = to_intel_connector(conn_state->connector);
	struct intel_panel *panel = &connector->panel;

	/* Nothing to do for AUX based backlight controls */
	if (panel->backlight.edp.intel.sdr_uses_aux)
	return;

	/* Note we want the actual pwm_level to be 0, regardless of pwm_min */
	panel->backlight.pwm_funcs->disable(conn_state, intel_backlight_invert_pwm_level(connector, 0));
	}

	static const char *dpcd_vs_pwm_str(bool aux)
	{
	return aux ? "DPCD" : "PWM";
	}

	static int
	intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pipe)
	{
	struct drm_i915_private *i915 = to_i915(connector->base.dev);
	struct intel_panel *panel = &connector->panel;
	struct drm_luminance_range_info *luminance_range =
	&connector->base.display_info.luminance_range;
	int ret;

	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] SDR backlight is controlled through %s\n",
	connector->base.base.id, connector->base.name,
	dpcd_vs_pwm_str(panel->backlight.edp.intel.sdr_uses_aux));

	if (!panel->backlight.edp.intel.sdr_uses_aux) {
	ret = panel->backlight.pwm_funcs->setup(connector, pipe);
	if (ret < 0) {
	drm_err(&i915->drm,
	"[CONNECTOR:%d:%s] Failed to setup SDR backlight controls through PWM: %d\n",
	connector->base.base.id, connector->base.name, ret);
	return ret;
	}
	}

	if (luminance_range->max_luminance) {
	panel->backlight.max = luminance_range->max_luminance;
	panel->backlight.min = luminance_range->min_luminance;
	} else {
	panel->backlight.max = 512;
	panel->backlight.min = 0;
	}

	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX HDR interface for backlight control (range %d..%d)\n",
	connector->base.base.id, connector->base.name,
	panel->backlight.min, panel->backlight.max);


	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
	panel->backlight.enabled = panel->backlight.level != 0;

	return 0;
	}

	/* VESA backlight callbacks */
	static u32 intel_dp_aux_vesa_get_backlight(struct intel_connector *connector, enum pipe unused)
	{
	return connector->panel.backlight.level;
	}

	static void
	intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state, u32 level)
	{
	struct intel_connector *connector = to_intel_connector(conn_state->connector);
	struct intel_panel *panel = &connector->panel;
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

	if (!panel->backlight.edp.vesa.info.aux_set) {
	const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);

	intel_backlight_set_pwm_level(conn_state, pwm_level);
	}

	drm_edp_backlight_set_level(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
	}

	static void
	intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
	const struct drm_connector_state *conn_state, u32 level)
	{
	struct intel_connector *connector = to_intel_connector(conn_state->connector);
	struct intel_panel *panel = &connector->panel;
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

	if (!panel->backlight.edp.vesa.info.aux_enable) {
	u32 pwm_level;

	if (!panel->backlight.edp.vesa.info.aux_set)
	pwm_level = intel_backlight_level_to_pwm(connector, level);
	else
	pwm_level = intel_backlight_invert_pwm_level(connector,
	panel->backlight.pwm_level_max);

	panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
	}

	drm_edp_backlight_enable(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
	}

	static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state *old_conn_state,
	u32 level)
	{
	struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
	struct intel_panel *panel = &connector->panel;
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

	drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.edp.vesa.info);

	if (!panel->backlight.edp.vesa.info.aux_enable)
	panel->backlight.pwm_funcs->disable(old_conn_state,
	intel_backlight_invert_pwm_level(connector, 0));
	}

	static int intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector, enum pipe pipe)
	{
	struct intel_dp *intel_dp = intel_attached_dp(connector);
	struct intel_panel *panel = &connector->panel;
	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
	u16 current_level;
	u8 current_mode;
	int ret;

	ret = drm_edp_backlight_init(&intel_dp->aux, &panel->backlight.edp.vesa.info,
	panel->vbt.backlight.pwm_freq_hz, intel_dp->edp_dpcd,
	&current_level, &current_mode);
	if (ret < 0)
	return ret;

	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX VESA backlight enable is controlled through %s\n",
	connector->base.base.id, connector->base.name,
	dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_enable));
	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX VESA backlight level is controlled through %s\n",
	connector->base.base.id, connector->base.name,
	dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_set));

	if (!panel->backlight.edp.vesa.info.aux_set \|\| !panel->backlight.edp.vesa.info.aux_enable) {
	ret = panel->backlight.pwm_funcs->setup(connector, pipe);
	if (ret < 0) {
	drm_err(&i915->drm,
	"[CONNECTOR:%d:%s] Failed to setup PWM backlight controls for eDP backlight: %d\n",
	connector->base.base.id, connector->base.name, ret);
	return ret;
	}
	}

	if (panel->backlight.edp.vesa.info.aux_set) {
	panel->backlight.max = panel->backlight.edp.vesa.info.max;
	panel->backlight.min = 0;
	if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
	panel->backlight.level = current_level;
	panel->backlight.enabled = panel->backlight.level != 0;
	} else {
	panel->backlight.level = panel->backlight.max;
	panel->backlight.enabled = false;
	}
	} else {
	panel->backlight.max = panel->backlight.pwm_level_max;
	panel->backlight.min = panel->backlight.pwm_level_min;
	if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_PWM) {
	panel->backlight.level = panel->backlight.pwm_funcs->get(connector, pipe);
	panel->backlight.enabled = panel->backlight.pwm_enabled;
	} else {
	panel->backlight.level = panel->backlight.max;
	panel->backlight.enabled = false;
	}
	}

	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX VESA interface for backlight control\n",
	connector->base.base.id, connector->base.name);

	return 0;
	}

	static bool
	intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
	{
	struct intel_dp *intel_dp = intel_attached_dp(connector);
	struct drm_i915_private *i915 = dp_to_i915(intel_dp);

	if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
	drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX Backlight Control Supported!\n",
	connector->base.base.id, connector->base.name);
	return true;
	}
	return false;
	}

	static const struct intel_panel_bl_funcs intel_dp_hdr_bl_funcs = {
	.setup = intel_dp_aux_hdr_setup_backlight,
	.enable = intel_dp_aux_hdr_enable_backlight,
	.disable = intel_dp_aux_hdr_disable_backlight,
	.set = intel_dp_aux_hdr_set_backlight,
	.get = intel_dp_aux_hdr_get_backlight,
	};

	static const struct intel_panel_bl_funcs intel_dp_vesa_bl_funcs = {
	.setup = intel_dp_aux_vesa_setup_backlight,
	.enable = intel_dp_aux_vesa_enable_backlight,
	.disable = intel_dp_aux_vesa_disable_backlight,
	.set = intel_dp_aux_vesa_set_backlight,
	.get = intel_dp_aux_vesa_get_backlight,
	};

	int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
	{
	struct drm_device *dev = connector->base.dev;
	struct intel_panel *panel = &connector->panel;
	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
	bool try_intel_interface = false, try_vesa_interface = false;

	/* Check the VBT and user's module parameters to figure out which
	* interfaces to probe
	*/
	switch (i915->display.params.enable_dpcd_backlight) {
	case INTEL_DP_AUX_BACKLIGHT_OFF:
	return -ENODEV;
	case INTEL_DP_AUX_BACKLIGHT_AUTO:
	switch (panel->vbt.backlight.type) {
	case INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE:
	try_vesa_interface = true;
	break;
	case INTEL_BACKLIGHT_DISPLAY_DDI:
	try_intel_interface = true;
	break;
	default:
	return -ENODEV;
	}
	break;
	case INTEL_DP_AUX_BACKLIGHT_ON:
	if (panel->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)
	try_intel_interface = true;

	try_vesa_interface = true;
	break;
	case INTEL_DP_AUX_BACKLIGHT_FORCE_VESA:
	try_vesa_interface = true;
	break;
	case INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL:
	try_intel_interface = true;
	break;
	}

	/*
	* Since Intel has their own backlight control interface, the majority of machines out there
	* using DPCD backlight controls with Intel GPUs will be using this interface as opposed to
	* the VESA interface. However, other GPUs (such as Nvidia's) will always use the VESA
	* interface. This means that there's quite a number of panels out there that will advertise
	* support for both interfaces, primarily systems with Intel/Nvidia hybrid GPU setups.
	*
	* There's a catch to this though: on many panels that advertise support for both
	* interfaces, the VESA backlight interface will stop working once we've programmed the
	* panel with Intel's OUI - which is also required for us to be able to detect Intel's
	* backlight interface at all. This means that the only sensible way for us to detect both
	* interfaces is to probe for Intel's first, and VESA's second.
	*/
	if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector)) {
	drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using Intel proprietary eDP backlight controls\n",
	connector->base.base.id, connector->base.name);
	panel->backlight.funcs = &intel_dp_hdr_bl_funcs;
	return 0;
	}

	if (try_vesa_interface && intel_dp_aux_supports_vesa_backlight(connector)) {
	drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using VESA eDP backlight controls\n",
	connector->base.base.id, connector->base.name);
	panel->backlight.funcs = &intel_dp_vesa_bl_funcs;
	return 0;
	}

	return -ENODEV;
	}