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Suraj Kandpal

2025-May-09 05:18 UTC

[PATCH 00/13] Modify drm helpers to use luminance

This series modifies drm dp edp helpers so that drivers can now use them
to manipulate brightness using luminance value via the
PANEL_TARGET_LUMINANCE_VALUE register. This feature was
introduced frin eDP 1.5.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>

Suraj Kandpal (13):
  drm/dp: Introduce new member in drm_backlight_info
  drm/dp: Add argument in drm_edp_backlight_init
  drm/dp: Add argument for luminance range info in
    drm_edp_backlight_init
  drm/dp: Move from u16 to u32 for max in drm_edp_backlight_info
  drm/dp: Change current_level argument type to u32
  drm/dp: Modify drm_edp_probe_state
  drm/dp: Change argument type for drm_edp_backlight_set_level
  drm/dp: Modify drm_edp_backlight_set_level
  drm/dp: Change argument type of drm_edp_backlight_enable
  drm/dp: Enable backlight control using luminance
  drm/i915/backlight: Use drm helper to initialize edp backlight
  drm/i915/backlight: Use drm helper to set edp backlight
  drm/i915/backlight: Use drm_edp_backlight_enable

 drivers/gpu/drm/display/drm_dp_helper.c       |  88 ++++++++---
 .../drm/i915/display/intel_dp_aux_backlight.c | 143 ++++++------------
 drivers/gpu/drm/nouveau/dispnv50/disp.c       |   2 +-
 drivers/gpu/drm/nouveau/nouveau_backlight.c   |   9 +-
 include/drm/display/drm_dp_helper.h           |  10 +-
 5 files changed, 126 insertions(+), 126 deletions(-)

-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 01/13] drm/dp: Introduce new member in drm_backlight_info

Introduce luminance_set flag which indicates if we can manipulate
backlight using luminance value or not which is only possible
after eDP v1.5.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 8 ++++++--
 include/drm/display/drm_dp_helper.h     | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 56c7e3318f01..ad8ba438e755 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4253,11 +4253,15 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct
drm_edp_backlight_info *bl
 		bl->aux_set = true;
 	if (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
 		bl->lsb_reg_used = true;
+	if ((edp_dpcd[0] & DP_EDP_15) && edp_dpcd[3] &
+	    (DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE))
+		bl->luminance_set = true;
 
 	/* Sanity check caps */
-	if (!bl->aux_set && !(edp_dpcd[2] &
DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
+	if (!bl->aux_set && !(edp_dpcd[2] &
DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP) &&
+	    !bl->luminance_set) {
 		drm_dbg_kms(aux->drm_dev,
-			    "%s: Panel supports neither AUX or PWM brightness control?
Aborting\n",
+			    "%s: Panel does not support AUX, PWM or luminance-based brightness
control. Aborting\n",
 			    aux->name);
 		return -EINVAL;
 	}
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index 7b19192c7031..fdc1a39529db 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -844,6 +844,7 @@ struct drm_edp_backlight_info {
 	bool lsb_reg_used : 1;
 	bool aux_enable : 1;
 	bool aux_set : 1;
+	bool luminance_set : 1;
 };
 
 int
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 02/13] drm/dp: Add argument in drm_edp_backlight_init

Add bool argument in drm_edp_backlight init to provide the drivers
option to choose if they want to use luminance values to
manipulate brightness.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c               | 7 ++++---
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 2 +-
 drivers/gpu/drm/nouveau/nouveau_backlight.c           | 2 +-
 include/drm/display/drm_dp_helper.h                   | 2 +-
 4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index ad8ba438e755..952b06414641 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4231,6 +4231,7 @@ drm_edp_backlight_probe_state(struct drm_dp_aux *aux,
struct drm_edp_backlight_i
  * @edp_dpcd: A cached copy of the eDP DPCD
  * @current_level: Where to store the probed brightness level, if any
  * @current_mode: Where to store the currently set backlight control mode
+ * @need_luminance: Tells us if a we want to manipulate backlight using
luminance values
  *
  * Initializes a &drm_edp_backlight_info struct by probing @aux for
it's backlight capabilities,
  * along with also probing the current and maximum supported brightness levels.
@@ -4243,7 +4244,7 @@ drm_edp_backlight_probe_state(struct drm_dp_aux *aux,
struct drm_edp_backlight_i
 int
 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info
*bl,
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
-		       u16 *current_level, u8 *current_mode)
+		       u16 *current_level, u8 *current_mode, bool need_luminance)
 {
 	int ret;
 
@@ -4254,7 +4255,7 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct
drm_edp_backlight_info *bl
 	if (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
 		bl->lsb_reg_used = true;
 	if ((edp_dpcd[0] & DP_EDP_15) && edp_dpcd[3] &
-	    (DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE))
+	    (DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE) && need_luminance)
 		bl->luminance_set = true;
 
 	/* Sanity check caps */
@@ -4372,7 +4373,7 @@ int drm_panel_dp_aux_backlight(struct drm_panel *panel,
struct drm_dp_aux *aux)
 	bl->aux = aux;
 
 	ret = drm_edp_backlight_init(aux, &bl->info, 0, edp_dpcd,
-				     &current_level, &current_mode);
+				     &current_level, &current_mode, false);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index 271b27c9de51..dc6f6680774f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -600,7 +600,7 @@ static int intel_dp_aux_vesa_setup_backlight(struct
intel_connector *connector,
 	} else {
 		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);
+					     &current_level, &current_mode, false);
 		if (ret < 0)
 			return ret;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c
b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index d47442125fa1..b938684a9422 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -262,7 +262,7 @@ nv50_backlight_init(struct nouveau_backlight *bl,
 				 nv_conn->base.name);
 
 			ret = drm_edp_backlight_init(&nv_conn->aux, &bl->edp_info, 0,
edp_dpcd,
-						     &current_level, &current_mode);
+						     &current_level, &current_mode, false);
 			if (ret < 0)
 				return ret;
 
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index fdc1a39529db..e984e8bc2398 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -850,7 +850,7 @@ struct drm_edp_backlight_info {
 int
 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info
*bl,
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
-		       u16 *current_level, u8 *current_mode);
+		       u16 *current_level, u8 *current_mode, bool need_luminance);
 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
 				u16 level);
 int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 03/13] drm/dp: Add argument for luminance range info in drm_edp_backlight_init

Add new argument to drm_edp_backlight_init which gives the
drm_luminance_range_info struct which will be needed to set the min
and max values for backlight.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c               | 5 ++++-
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 5 +++--
 drivers/gpu/drm/nouveau/nouveau_backlight.c           | 5 ++++-
 include/drm/display/drm_dp_helper.h                   | 1 +
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 952b06414641..8d0f8366fd4a 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4227,6 +4227,8 @@ drm_edp_backlight_probe_state(struct drm_dp_aux *aux,
struct drm_edp_backlight_i
  * interface.
  * @aux: The DP aux device to use for probing
  * @bl: The &drm_edp_backlight_info struct to fill out with information on
the backlight
+ * @lr: The &drm_luminance_range_info struct which is used to get the min
max when using
+ *luminance override
  * @driver_pwm_freq_hz: Optional PWM frequency from the driver in hz
  * @edp_dpcd: A cached copy of the eDP DPCD
  * @current_level: Where to store the probed brightness level, if any
@@ -4243,6 +4245,7 @@ drm_edp_backlight_probe_state(struct drm_dp_aux *aux,
struct drm_edp_backlight_i
  */
 int
 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info
*bl,
+		       struct drm_luminance_range_info *lr,
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
 		       u16 *current_level, u8 *current_mode, bool need_luminance)
 {
@@ -4372,7 +4375,7 @@ int drm_panel_dp_aux_backlight(struct drm_panel *panel,
struct drm_dp_aux *aux)
 
 	bl->aux = aux;
 
-	ret = drm_edp_backlight_init(aux, &bl->info, 0, edp_dpcd,
+	ret = drm_edp_backlight_init(aux, &bl->info, NULL, 0, edp_dpcd,
 				     &current_level, &current_mode, false);
 	if (ret < 0)
 		return ret;
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index dc6f6680774f..a4fee7c622ee 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -599,8 +599,9 @@ static int intel_dp_aux_vesa_setup_backlight(struct
intel_connector *connector,
 			    connector->base.base.id, connector->base.name);
 	} else {
 		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, false);
+					     luminance_range, panel->vbt.backlight.pwm_freq_hz,
+					     intel_dp->edp_dpcd, &current_level, &current_mode,
+					     false);
 		if (ret < 0)
 			return ret;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c
b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index b938684a9422..a3681e101d56 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -234,6 +234,8 @@ nv50_backlight_init(struct nouveau_backlight *bl,
 		    const struct backlight_ops **ops)
 {
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
+	struct drm_luminance_range_info *luminance_range +	
&nv_conn->base.display_info.luminance_range;
 
 	/*
 	 * Note when this runs the connectors have not been probed yet,
@@ -261,7 +263,8 @@ nv50_backlight_init(struct nouveau_backlight *bl,
 			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,
+			ret = drm_edp_backlight_init(&nv_conn->aux, &bl->edp_info,
+						     luminance_range, 0, edp_dpcd,
 						     &current_level, &current_mode, false);
 			if (ret < 0)
 				return ret;
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index e984e8bc2398..6ec165dc5e56 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -849,6 +849,7 @@ struct drm_edp_backlight_info {
 
 int
 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info
*bl,
+		       struct drm_luminance_range_info *lr,
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
 		       u16 *current_level, u8 *current_mode, bool need_luminance);
 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 04/13] drm/dp: Move from u16 to u32 for max in drm_edp_backlight_info

Use u32 instead of u16 for max variable in drm_edp_backlight_info
since it can now hold max luminance range value which is u32.
We will set this max with max_luminance value when luminance_set is
true.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 10 +++++++---
 include/drm/display/drm_dp_helper.h     |  2 +-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 8d0f8366fd4a..1ba2ce99feac 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4270,9 +4270,13 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct
drm_edp_backlight_info *bl
 		return -EINVAL;
 	}
 
-	ret = drm_edp_backlight_probe_max(aux, bl, driver_pwm_freq_hz, edp_dpcd);
-	if (ret < 0)
-		return ret;
+	if (bl->luminance_set) {
+		bl->max = lr->max_luminance;
+	} else {
+		ret = drm_edp_backlight_probe_max(aux, bl, driver_pwm_freq_hz, edp_dpcd);
+		if (ret < 0)
+			return ret;
+	}
 
 	ret = drm_edp_backlight_probe_state(aux, bl, current_mode);
 	if (ret < 0)
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index 6ec165dc5e56..3f78e9649b0d 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -839,7 +839,7 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum
drm_dp_quirk quirk)
 struct drm_edp_backlight_info {
 	u8 pwmgen_bit_count;
 	u8 pwm_freq_pre_divider;
-	u16 max;
+	u32 max;
 
 	bool lsb_reg_used : 1;
 	bool aux_enable : 1;
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 05/13] drm/dp: Change current_level argument type to u32

Change the current_level argument type to u32 from u16
since it can now carry the value which it gets from
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c               | 4 ++--
 drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 2 +-
 drivers/gpu/drm/nouveau/nouveau_backlight.c           | 2 +-
 include/drm/display/drm_dp_helper.h                   | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 1ba2ce99feac..6588be6605b6 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4247,7 +4247,7 @@ int
 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info
*bl,
 		       struct drm_luminance_range_info *lr,
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
-		       u16 *current_level, u8 *current_mode, bool need_luminance)
+		       u32 *current_level, u8 *current_mode, bool need_luminance)
 {
 	int ret;
 
@@ -4355,7 +4355,7 @@ int drm_panel_dp_aux_backlight(struct drm_panel *panel,
struct drm_dp_aux *aux)
 {
 	struct dp_aux_backlight *bl;
 	struct backlight_properties props = { 0 };
-	u16 current_level;
+	u32 current_level;
 	u8 current_mode;
 	u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
 	int ret;
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index a4fee7c622ee..5441a7199102 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -580,7 +580,7 @@ static int intel_dp_aux_vesa_setup_backlight(struct
intel_connector *connector,
 		&connector->base.display_info.luminance_range;
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct intel_panel *panel = &connector->panel;
-	u16 current_level;
+	u32 current_level;
 	u8 current_mode;
 	int ret;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c
b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index a3681e101d56..a430ee30060e 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -247,7 +247,7 @@ nv50_backlight_init(struct nouveau_backlight *bl,
 
 	if (nv_conn->type == DCB_CONNECTOR_eDP) {
 		int ret;
-		u16 current_level;
+		u32 current_level;
 		u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
 		u8 current_mode;
 
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index 3f78e9649b0d..8acc20a3b80a 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -851,7 +851,7 @@ int
 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info
*bl,
 		       struct drm_luminance_range_info *lr,
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
-		       u16 *current_level, u8 *current_mode, bool need_luminance);
+		       u32 *current_level, u8 *current_mode, bool need_luminance);
 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
 				u16 level);
 int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 06/13] drm/dp: Modify drm_edp_probe_state

Modify drm_edp_probe_state to read current level from
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE. We divide it by
1000 since the value in this register is in millinits.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 35 ++++++++++++++++++-------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 6588be6605b6..0c90f161bf4d 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4185,7 +4185,7 @@ drm_edp_backlight_probe_state(struct drm_dp_aux *aux,
struct drm_edp_backlight_i
 			      u8 *current_mode)
 {
 	int ret;
-	u8 buf[2];
+	u8 buf[3];
 	u8 mode_reg;
 
 	ret = drm_dp_dpcd_read_byte(aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
&mode_reg);
@@ -4202,17 +4202,32 @@ drm_edp_backlight_probe_state(struct drm_dp_aux *aux,
struct drm_edp_backlight_i
 	if (*current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
 		int size = 1 + bl->lsb_reg_used;
 
-		ret = drm_dp_dpcd_read_data(aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, buf, size);
-		if (ret < 0) {
-			drm_dbg_kms(aux->drm_dev, "%s: Failed to read backlight level:
%d\n",
-				    aux->name, ret);
-			return ret;
+		if (bl->luminance_set) {
+			ret = drm_dp_dpcd_read_data(aux, DP_EDP_PANEL_TARGET_LUMINANCE_VALUE,
+						    buf, sizeof(buf));
+			if (ret < 0) {
+				drm_dbg_kms(aux->drm_dev,
+					    "%s: Failed to read backlight level: %d\n",
+					    aux->name, ret);
+				return ret;
 		}
 
-		if (bl->lsb_reg_used)
-			return (buf[0] << 8) | buf[1];
-		else
-			return buf[0];
+		return (buf[0] | buf[1] << 8 | buf[2] << 16) / 1000;
+		} else {
+			ret = drm_dp_dpcd_read_data(aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+						    buf, size);
+			if (ret < 0) {
+				drm_dbg_kms(aux->drm_dev,
+					    "%s: Failed to read backlight level: %d\n",
+					    aux->name, ret);
+				return ret;
+			}
+
+			if (bl->lsb_reg_used)
+				return (buf[0] << 8) | buf[1];
+			else
+				return buf[0];
+		}
 	}
 
 	/*
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 07/13] drm/dp: Change argument type for drm_edp_backlight_set_level

Use u32 for level variable as one may need to pass value for
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE.

--v2
-Typecase is not needed [Jani]

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 include/drm/display/drm_dp_helper.h     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index 0c90f161bf4d..b17f9e75d93f 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -3933,7 +3933,7 @@ EXPORT_SYMBOL(drm_dp_pcon_convert_rgb_to_ycbcr);
  * Returns: %0 on success, negative error code on failure
  */
 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-				u16 level)
+				u32 level)
 {
 	int ret;
 	u8 buf[2] = { 0 };
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index 8acc20a3b80a..88b858048746 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -853,7 +853,7 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct
drm_edp_backlight_info *bl
 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
 		       u32 *current_level, u8 *current_mode, bool need_luminance);
 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-				u16 level);
+				u32 level);
 int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
 			     u16 level);
 int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl);
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 08/13] drm/dp: Modify drm_edp_backlight_set_level

Modify drm_edp_backlight_set_level to be able to set the value
for register in DP_EDP_PANEL_TARGET_LUMINANCE_VALUE. We multiply
the level with 1000 since we get the value in Nits and the
register accepts it in milliNits.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index b17f9e75d93f..b0688945649b 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -3936,20 +3936,28 @@ int drm_edp_backlight_set_level(struct drm_dp_aux *aux,
const struct drm_edp_bac
 				u32 level)
 {
 	int ret;
-	u8 buf[2] = { 0 };
+	unsigned int offset = DP_EDP_BACKLIGHT_BRIGHTNESS_MSB;
+	u8 buf[3] = { 0 };
 
 	/* The panel uses the PWM for controlling brightness levels */
-	if (!bl->aux_set)
+	if (!(bl->aux_set || bl->luminance_set))
 		return 0;
 
-	if (bl->lsb_reg_used) {
+	if (bl->luminance_set) {
+		level = level * 1000;
+		level &= 0xffffff;
+		buf[0] = (level & 0x0000ff);
+		buf[1] = (level & 0x00ff00) >> 8;
+		buf[2] = (level & 0xff0000) >> 16;
+		offset = DP_EDP_PANEL_TARGET_LUMINANCE_VALUE;
+	} else if (bl->lsb_reg_used) {
 		buf[0] = (level & 0xff00) >> 8;
 		buf[1] = (level & 0x00ff);
 	} else {
 		buf[0] = level;
 	}
 
-	ret = drm_dp_dpcd_write_data(aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, buf,
sizeof(buf));
+	ret = drm_dp_dpcd_write_data(aux, offset, buf, sizeof(buf));
 	if (ret < 0) {
 		drm_err(aux->drm_dev,
 			"%s: Failed to write aux backlight level: %d\n",
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 09/13] drm/dp: Change argument type of drm_edp_backlight_enable

Change the argument type to u32 for the default level being sent
since it has to now account for luminance value which has to be
set for DP_EDP_PANEL_LUMINANCE_TARGET_VALUE.

--v2
-No need to typecast [Jani]

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 2 +-
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +-
 include/drm/display/drm_dp_helper.h     | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index b0688945649b..f99e3ae78eac 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4020,7 +4020,7 @@ drm_edp_backlight_set_enable(struct drm_dp_aux *aux, const
struct drm_edp_backli
  * Returns: %0 on success, negative error code on failure.
  */
 int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-			     const u16 level)
+			     const u32 level)
 {
 	int ret;
 	u8 dpcd_buf;
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 9bed728cb00e..0f29e1f0e0b1 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1829,7 +1829,7 @@ nv50_sor_atomic_enable(struct drm_encoder *encoder, struct
drm_atomic_state *sta
 		backlight = nv_connector->backlight;
 		if (backlight && backlight->uses_dpcd)
 			drm_edp_backlight_enable(&nv_connector->aux,
&backlight->edp_info,
-						 (u16)backlight->dev->props.brightness);
+						 backlight->dev->props.brightness);
 #endif
 
 		break;
diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
index 88b858048746..eca4b3b701b0 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -855,7 +855,7 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct
drm_edp_backlight_info *bl
 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
 				u32 level);
 int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl,
-			     u16 level);
+			     u32 level);
 int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct
drm_edp_backlight_info *bl);
 
 #if IS_ENABLED(CONFIG_DRM_KMS_HELPER) &&
(IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 10/13] drm/dp: Enable backlight control using luminance

Add flag to enable brightness control via luminance value
when enabling edp backlight.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
index f99e3ae78eac..1643907b3916 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4030,6 +4030,9 @@ int drm_edp_backlight_enable(struct drm_dp_aux *aux, const
struct drm_edp_backli
 	else
 		dpcd_buf = DP_EDP_BACKLIGHT_CONTROL_MODE_PWM;
 
+	if (bl->luminance_set)
+		dpcd_buf |= DP_EDP_PANEL_LUMINANCE_CONTROL_ENABLE;
+
 	if (bl->pwmgen_bit_count) {
 		ret = drm_dp_dpcd_write_byte(aux, DP_EDP_PWMGEN_BIT_COUNT,
bl->pwmgen_bit_count);
 		if (ret < 0)
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 11/13] drm/i915/backlight: Use drm helper to initialize edp backlight

Now that drm_edp_backlight init has been to be able to setup
brightness manipulation via luminance we can just use that.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 .../drm/i915/display/intel_dp_aux_backlight.c | 100 +++++++++---------
 1 file changed, 49 insertions(+), 51 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index 5441a7199102..b97f778d420e 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -584,9 +584,36 @@ static int intel_dp_aux_vesa_setup_backlight(struct
intel_connector *connector,
 	u8 current_mode;
 	int ret;
 
-	if (panel->backlight.edp.vesa.luminance_control_support) {
+	ret = drm_edp_backlight_init(&intel_dp->aux,
&panel->backlight.edp.vesa.info,
+				     luminance_range, panel->vbt.backlight.pwm_freq_hz,
+				     intel_dp->edp_dpcd, &current_level, &current_mode, true);
+	if (ret < 0)
+		return ret;
+
+	drm_dbg_kms(display->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(display->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.luminance_set ||
+	    !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(display->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.luminance_set) {
 		if (luminance_range->max_luminance) {
-			panel->backlight.max = luminance_range->max_luminance;
+			panel->backlight.max = panel->backlight.edp.vesa.info.max;
 			panel->backlight.min = luminance_range->min_luminance;
 		} else {
 			panel->backlight.max = 512;
@@ -595,57 +622,28 @@ static int intel_dp_aux_vesa_setup_backlight(struct
intel_connector *connector,
 		panel->backlight.level = intel_dp_aux_vesa_get_backlight(connector, 0);
 		panel->backlight.enabled = panel->backlight.level != 0;
 		drm_dbg_kms(display->drm,
-			    "[CONNECTOR:%d:%s] AUX VESA Nits backlight level is controlled
through DPCD\n",
-			    connector->base.base.id, connector->base.name);
-	} else {
-		ret = drm_edp_backlight_init(&intel_dp->aux,
&panel->backlight.edp.vesa.info,
-					     luminance_range, panel->vbt.backlight.pwm_freq_hz,
-					     intel_dp->edp_dpcd, &current_level, &current_mode,
-					     false);
-		if (ret < 0)
-			return ret;
-
-		drm_dbg_kms(display->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(display->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(display->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;
-			}
+		    "[CONNECTOR:%d:%s] AUX VESA Nits backlight level is controlled
through DPCD\n",
+		    connector->base.base.id, connector->base.name);
+	} else 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;
 		}
-
-		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.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;
-			}
+			panel->backlight.level = panel->backlight.max;
+			panel->backlight.enabled = false;
 		}
 	}
 
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 12/13] drm/i915/backlight: Use drm helper to set edp backlight

Now that the drm helper sets the backlight using luminance
too we can use that. Remove the obselete function.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 .../drm/i915/display/intel_dp_aux_backlight.c | 34 ++-----------------
 1 file changed, 3 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index b97f778d420e..a81c3f0ac3cb 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -475,31 +475,6 @@ static u32 intel_dp_aux_vesa_get_backlight(struct
intel_connector *connector, en
 	return connector->panel.backlight.level;
 }
 
-static int
-intel_dp_aux_vesa_set_luminance(struct intel_connector *connector, u32 level)
-{
-	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
-	u8 buf[3];
-	int ret;
-
-	level = level * 1000;
-	level &= 0xffffff;
-	buf[0] = (level & 0x0000ff);
-	buf[1] = (level & 0x00ff00) >> 8;
-	buf[2] = (level & 0xff0000) >> 16;
-
-	ret = drm_dp_dpcd_write(&intel_dp->aux,
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE,
-				buf, sizeof(buf));
-	if (ret != sizeof(buf)) {
-		drm_err(intel_dp->aux.drm_dev,
-			"%s: Failed to set VESA Aux Luminance: %d\n",
-			intel_dp->aux.name, ret);
-		return -EINVAL;
-	} else {
-		return 0;
-	}
-}
-
 static void
 intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state,
u32 level)
 {
@@ -507,11 +482,6 @@ intel_dp_aux_vesa_set_backlight(const struct
drm_connector_state *conn_state, u3
 	struct intel_panel *panel = &connector->panel;
 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 
-	if (panel->backlight.edp.vesa.luminance_control_support) {
-		if (!intel_dp_aux_vesa_set_luminance(connector, level))
-			return;
-	}
-
 	if (!panel->backlight.edp.vesa.info.aux_set) {
 		const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
 
@@ -537,7 +507,9 @@ intel_dp_aux_vesa_enable_backlight(const struct
intel_crtc_state *crtc_state,
 		if (ret == 1)
 			return;
 
-		if (!intel_dp_aux_vesa_set_luminance(connector, level))
+		if (!drm_edp_backlight_set_level(&intel_dp->aux,
+						 &panel->backlight.edp.vesa.info,
+						 level))
 			return;
 	}
 
-- 
2.34.1

Suraj Kandpal

2025-May-09 05:18 UTC

head link

[PATCH 13/13] drm/i915/backlight: Use drm_edp_backlight_enable

Use drm dp helper to enable backlight now that it has been modified
to set PANEL_LUMINANCE_CONTROL_ENABLE bit based on if capability
supports it and the driver wants it. Remove the dead code.

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 .../gpu/drm/i915/display/intel_dp_aux_backlight.c  | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
index a81c3f0ac3cb..3faba358fed8 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -498,20 +498,6 @@ intel_dp_aux_vesa_enable_backlight(const struct
intel_crtc_state *crtc_state,
 	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);
-	int ret;
-
-	if (panel->backlight.edp.vesa.luminance_control_support) {
-		ret = drm_dp_dpcd_writeb(&intel_dp->aux,
DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
-					 DP_EDP_PANEL_LUMINANCE_CONTROL_ENABLE);
-
-		if (ret == 1)
-			return;
-
-		if (!drm_edp_backlight_set_level(&intel_dp->aux,
-						 &panel->backlight.edp.vesa.info,
-						 level))
-			return;
-	}
 
 	if (!panel->backlight.edp.vesa.info.aux_enable) {
 		u32 pwm_level;
-- 
2.34.1

Nouveau - May 2025 - [PATCH 08/13] drm/dp: Modify drm_edp_backlight_set_level

[PATCH 00/13] Modify drm helpers to use luminance

[PATCH 01/13] drm/dp: Introduce new member in drm_backlight_info

[PATCH 02/13] drm/dp: Add argument in drm_edp_backlight_init

[PATCH 03/13] drm/dp: Add argument for luminance range info in drm_edp_backlight_init

[PATCH 04/13] drm/dp: Move from u16 to u32 for max in drm_edp_backlight_info

[PATCH 05/13] drm/dp: Change current_level argument type to u32

[PATCH 06/13] drm/dp: Modify drm_edp_probe_state

[PATCH 07/13] drm/dp: Change argument type for drm_edp_backlight_set_level

[PATCH 08/13] drm/dp: Modify drm_edp_backlight_set_level

[PATCH 09/13] drm/dp: Change argument type of drm_edp_backlight_enable

[PATCH 10/13] drm/dp: Enable backlight control using luminance

[PATCH 11/13] drm/i915/backlight: Use drm helper to initialize edp backlight

[PATCH 12/13] drm/i915/backlight: Use drm helper to set edp backlight

[PATCH 13/13] drm/i915/backlight: Use drm_edp_backlight_enable