[PATCH 3/3] drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

[PATCH 3/3] drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

[Yetunde Adebisi]

This patch adds support for eDP backlight control using DPCD registers to
backlight hooks in intel_panel.

It checks for backlight control over AUX channel capability and sets up
function pointers to get and set the backlight brightness level if
supported.

v2: Moved backlight functions from intel_dp.c into a new file
intel_dp_aux_backlight.c. Also moved reading of eDP display control
registers to intel_dp_get_dpcd

v3: Correct some formatting mistakes

v4: Updated to use AUX backlight control if PWM control is not possible
	(Jani)
v5: Moved call to initialize backlight registers to dp_aux_setup_backlight
v6: Check DP_EDP_BACKLIGHT_PIN_ENABLE_CAP is disabled before setting up AUX
backlight control. To fix BLM_PWM_ENABLE igt test warnings on bdw_ultra
v7: Add enable_dpcd_backlight module parameter.
v8: Rebase onto latest drm-intel-nightly branch
v9: Remove changes to intel_dp_dpcd_read_wake
    Split addition edp_dpcd variable into a separate patch

Cc: Bob Paauwe <bob.j.paauwe@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>
---
 drivers/gpu/drm/i915/Makefile                 |   1 +
 drivers/gpu/drm/i915/i915_params.c            |   4 +
 drivers/gpu/drm/i915/i915_params.h            |   1 +
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 173 ++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h              |   3 +
 drivers/gpu/drm/i915/intel_panel.c            |   4 +
 6 files changed, 186 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 7ffb51b..11cc3e6 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -79,6 +79,7 @@ i915-y += dvo_ch7017.o \
 	  dvo_tfp410.o \
 	  intel_crt.o \
 	  intel_ddi.o \
+	  intel_dp_aux_backlight.o \
 	  intel_dp_link_training.o \
 	  intel_dp_mst.o \
 	  intel_dp.o \
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 1779f02..383c076 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -58,6 +58,7 @@ struct i915_params i915 __read_mostly = {
 	.guc_log_level = -1,
 	.enable_dp_mst = true,
 	.inject_load_failure = 0,
+	.enable_dpcd_backlight = false,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -210,3 +211,6 @@ MODULE_PARM_DESC(enable_dp_mst,
 module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
 MODULE_PARM_DESC(inject_load_failure,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
+module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
+MODULE_PARM_DESC(enable_dpcd_backlight,
+	"Enable support for DPCD backlight control (default:false)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 02bc278..65e73dd 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -61,6 +61,7 @@ struct i915_params {
 	bool verbose_state_checks;
 	bool nuclear_pageflip;
 	bool enable_dp_mst;
+	bool enable_dpcd_backlight;
 };
 
 extern struct i915_params i915 __read_mostly;
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
new file mode 100644
index 0000000..984fb0d
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -0,0 +1,173 @@
+/*
+ * 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.
+ *
+ */
+
+#include "intel_drv.h"
+
+static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
+{
+	uint8_t reg_val = 0;
+
+	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+			&reg_val) < 0) {
+		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+				DP_EDP_DISPLAY_CONTROL_REGISTER);
+		return;
+	}
+	if (enable)
+		reg_val |= DP_EDP_BACKLIGHT_ENABLE;
+	else
+		reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+			reg_val) != 1) {
+		DRM_DEBUG_KMS("Failed to %s aux backlight\n",
+				enable ? "enable" : "disable");
+	}
+}
+
+/*
+ * Read the current backlight value from DPCD register(s) based
+ * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
+ */
+static uint32_t intel_dp_aux_get_backlight(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t read_val[2] = { 0x0 };
+	uint16_t level = 0;
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+			&read_val, sizeof(read_val)) < 0) {
+		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+				DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
+		return 0;
+	}
+	level = read_val[0];
+	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+		level = (read_val[0] << 8 | read_val[1]);
+
+	return level;
+}
+
+/*
+ * Sends the current backlight level over the aux channel, checking if its using
+ * 8-bit or 16 bit value (MSB and LSB)
+ */
+static void
+intel_dp_aux_set_backlight(struct intel_connector *connector, u32 level)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t vals[2] = { 0x0 };
+
+	vals[0] = level;
+
+	/* Write the MSB and/or LSB */
+	 if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
+		vals[0] = (level & 0xFF00) >> 8;
+		vals[1] = (level & 0xFF);
+	}
+	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+			vals, sizeof(vals)) < 0) {
+		DRM_DEBUG_KMS("Failed to write aux backlight level\n");
+		return;
+	}
+}
+
+static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t dpcd_buf = 0;
+
+	set_aux_backlight_enable(intel_dp, true);
+
+	if ((drm_dp_dpcd_readb(&intel_dp->aux,
+			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) == 1) &&
+			((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
+					DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
+		drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+				(dpcd_buf | DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
+}
+
+static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
+{
+	set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base), false);
+}
+
+static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
+			enum pipe pipe)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	struct intel_panel *panel = &connector->panel;
+
+	intel_dp_aux_enable_backlight(connector);
+
+	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+		panel->backlight.max = 0xFFFF;
+	else
+		panel->backlight.max = 0xFF;
+
+	panel->backlight.min = 0;
+	panel->backlight.level = intel_dp_aux_get_backlight(connector);
+
+	panel->backlight.enabled = panel->backlight.level != 0;
+
+	return 0;
+}
+
+static bool
+intel_dp_aux_display_control_capable(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+
+	/* Check the  eDP Display control capabilities registers to determine if
+	 * the panel can support backlight control over the aux channel
+	 */
+	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
+			(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
+			!((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
+					(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
+
+		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
+		return true;
+	}
+	return false;
+}
+
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+{
+	struct intel_panel *panel = &intel_connector->panel;
+
+	if(!i915.enable_dpcd_backlight)
+		return -ENODEV;
+
+	if (!intel_dp_aux_display_control_capable(intel_connector))
+		return -ENODEV;
+
+	panel->backlight.setup = intel_dp_aux_setup_backlight;
+	panel->backlight.enable = intel_dp_aux_enable_backlight;
+	panel->backlight.disable = intel_dp_aux_disable_backlight;
+	panel->backlight.set = intel_dp_aux_set_backlight;
+	panel->backlight.get = intel_dp_aux_get_backlight;
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b14e515..cefdb6b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1322,6 +1322,9 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
 bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
 
+/* intel_dp_aux_backlight.c */
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
+
 /* intel_dp_mst.c */
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 8c8996f..aab5153 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1718,6 +1718,10 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
 		container_of(panel, struct intel_connector, panel);
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 
+	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
+			intel_dp_aux_init_backlight_funcs(connector) == 0)
+		return;
+
 	if (IS_BROXTON(dev_priv)) {
 		panel->backlight.setup = bxt_setup_backlight;
 		panel->backlight.enable = bxt_enable_backlight;
-- 
1.9.3

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

[PATCH 3/3] drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

[Yetunde Adebisi]

This patch adds support for eDP backlight control using DPCD registers to
backlight hooks in intel_panel.

It checks for backlight control over AUX channel capability and sets up
function pointers to get and set the backlight brightness level if
supported.

v2: Moved backlight functions from intel_dp.c into a new file
intel_dp_aux_backlight.c. Also moved reading of eDP display control
registers to intel_dp_get_dpcd

v3: Correct some formatting mistakes

v4: Updated to use AUX backlight control if PWM control is not possible
	(Jani)
v5: Moved call to initialize backlight registers to dp_aux_setup_backlight
v6: Check DP_EDP_BACKLIGHT_PIN_ENABLE_CAP is disabled before setting up AUX
backlight control. To fix BLM_PWM_ENABLE igt test warnings on bdw_ultra
v7: Add enable_dpcd_backlight module parameter.
v8: Rebase onto latest drm-intel-nightly branch
v9: Remove changes to intel_dp_dpcd_read_wake
    Split addition edp_dpcd variable into a separate patch

Cc: Bob Paauwe <bob.j.paauwe@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>
---
 drivers/gpu/drm/i915/Makefile                 |   1 +
 drivers/gpu/drm/i915/i915_params.c            |   4 +
 drivers/gpu/drm/i915/i915_params.h            |   1 +
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 173 ++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h              |   3 +
 drivers/gpu/drm/i915/intel_panel.c            |   4 +
 6 files changed, 186 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 7ffb51b..11cc3e6 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -79,6 +79,7 @@ i915-y += dvo_ch7017.o \
 	  dvo_tfp410.o \
 	  intel_crt.o \
 	  intel_ddi.o \
+	  intel_dp_aux_backlight.o \
 	  intel_dp_link_training.o \
 	  intel_dp_mst.o \
 	  intel_dp.o \
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 1779f02..383c076 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -58,6 +58,7 @@ struct i915_params i915 __read_mostly = {
 	.guc_log_level = -1,
 	.enable_dp_mst = true,
 	.inject_load_failure = 0,
+	.enable_dpcd_backlight = false,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -210,3 +211,6 @@ MODULE_PARM_DESC(enable_dp_mst,
 module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
 MODULE_PARM_DESC(inject_load_failure,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
+module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
+MODULE_PARM_DESC(enable_dpcd_backlight,
+	"Enable support for DPCD backlight control (default:false)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 02bc278..65e73dd 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -61,6 +61,7 @@ struct i915_params {
 	bool verbose_state_checks;
 	bool nuclear_pageflip;
 	bool enable_dp_mst;
+	bool enable_dpcd_backlight;
 };
 
 extern struct i915_params i915 __read_mostly;
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
new file mode 100644
index 0000000..984fb0d
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -0,0 +1,173 @@
+/*
+ * 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.
+ *
+ */
+
+#include "intel_drv.h"
+
+static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
+{
+	uint8_t reg_val = 0;
+
+	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+			&reg_val) < 0) {
+		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+				DP_EDP_DISPLAY_CONTROL_REGISTER);
+		return;
+	}
+	if (enable)
+		reg_val |= DP_EDP_BACKLIGHT_ENABLE;
+	else
+		reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+			reg_val) != 1) {
+		DRM_DEBUG_KMS("Failed to %s aux backlight\n",
+				enable ? "enable" : "disable");
+	}
+}
+
+/*
+ * Read the current backlight value from DPCD register(s) based
+ * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
+ */
+static uint32_t intel_dp_aux_get_backlight(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t read_val[2] = { 0x0 };
+	uint16_t level = 0;
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+			&read_val, sizeof(read_val)) < 0) {
+		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+				DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
+		return 0;
+	}
+	level = read_val[0];
+	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+		level = (read_val[0] << 8 | read_val[1]);
+
+	return level;
+}
+
+/*
+ * Sends the current backlight level over the aux channel, checking if its using
+ * 8-bit or 16 bit value (MSB and LSB)
+ */
+static void
+intel_dp_aux_set_backlight(struct intel_connector *connector, u32 level)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t vals[2] = { 0x0 };
+
+	vals[0] = level;
+
+	/* Write the MSB and/or LSB */
+	 if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
+		vals[0] = (level & 0xFF00) >> 8;
+		vals[1] = (level & 0xFF);
+	}
+	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+			vals, sizeof(vals)) < 0) {
+		DRM_DEBUG_KMS("Failed to write aux backlight level\n");
+		return;
+	}
+}
+
+static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t dpcd_buf = 0;
+
+	set_aux_backlight_enable(intel_dp, true);
+
+	if ((drm_dp_dpcd_readb(&intel_dp->aux,
+			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) == 1) &&
+			((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
+					DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
+		drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+				(dpcd_buf | DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
+}
+
+static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
+{
+	set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base), false);
+}
+
+static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
+			enum pipe pipe)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	struct intel_panel *panel = &connector->panel;
+
+	intel_dp_aux_enable_backlight(connector);
+
+	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+		panel->backlight.max = 0xFFFF;
+	else
+		panel->backlight.max = 0xFF;
+
+	panel->backlight.min = 0;
+	panel->backlight.level = intel_dp_aux_get_backlight(connector);
+
+	panel->backlight.enabled = panel->backlight.level != 0;
+
+	return 0;
+}
+
+static bool
+intel_dp_aux_display_control_capable(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+
+	/* Check the  eDP Display control capabilities registers to determine if
+	 * the panel can support backlight control over the aux channel
+	 */
+	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
+			(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
+			!((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
+					(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
+
+		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
+		return true;
+	}
+	return false;
+}
+
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+{
+	struct intel_panel *panel = &intel_connector->panel;
+
+	if(!i915.enable_dpcd_backlight)
+		return -ENODEV;
+
+	if (!intel_dp_aux_display_control_capable(intel_connector))
+		return -ENODEV;
+
+	panel->backlight.setup = intel_dp_aux_setup_backlight;
+	panel->backlight.enable = intel_dp_aux_enable_backlight;
+	panel->backlight.disable = intel_dp_aux_disable_backlight;
+	panel->backlight.set = intel_dp_aux_set_backlight;
+	panel->backlight.get = intel_dp_aux_get_backlight;
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b14e515..cefdb6b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1322,6 +1322,9 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
 bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
 
+/* intel_dp_aux_backlight.c */
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
+
 /* intel_dp_mst.c */
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 8c8996f..aab5153 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1718,6 +1718,10 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
 		container_of(panel, struct intel_connector, panel);
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 
+	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
+			intel_dp_aux_init_backlight_funcs(connector) == 0)
+		return;
+
 	if (IS_BROXTON(dev_priv)) {
 		panel->backlight.setup = bxt_setup_backlight;
 		panel->backlight.enable = bxt_enable_backlight;
-- 
1.9.3

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[PATCH 0/3] DPCD Backlight Control

[Yetunde Adebisi]

These patches add support for Backlight Control using DPCD registers on eDP 
displays.

- Patch 1 Adds macro for DPCD registers capability size to drm_dp_helper.h
- Patch 2 Reads the eDP DPCD Display Control capability registers.
- Patch 3 Implements functionaly for DPCD Backlight Control 

Yetunde Adebisi (3):
  drm/dp: Add definition for Display Control DPCD Registers capability
    size
  drm/i915: Read eDP Display control capability registers
  drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

 drivers/gpu/drm/i915/Makefile                 |   1 +
 drivers/gpu/drm/i915/i915_params.c            |   4 +
 drivers/gpu/drm/i915/i915_params.h            |   1 +
 drivers/gpu/drm/i915/intel_dp.c               |  15 ++-
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 173 ++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h              |   4 +
 drivers/gpu/drm/i915/intel_panel.c            |   4 +
 include/drm/drm_dp_helper.h                   |   1 +
 8 files changed, 198 insertions(+), 5 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight.c

-- 
1.9.3

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[PATCH 1/3] drm/dp: Add definition for Display Control DPCD Registers capability size

[Yetunde Adebisi]

This is used when reading Display Control capability Registers on the sink
device.

cc: Jani Nikula <jani.nikula@intel.com>
cc: dri-devel@lists.freedesktop.org
Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
---
 include/drm/drm_dp_helper.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 1252108..92d9a52 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -621,6 +621,7 @@ u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SI
 #define DP_BRANCH_OUI_HEADER_SIZE	0xc
 #define DP_RECEIVER_CAP_SIZE		0xf
 #define EDP_PSR_RECEIVER_CAP_SIZE	2
+#define EDP_DISPLAY_CTL_CAP_SIZE	3
 
 void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
-- 
1.9.3

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[PATCH 2/3] drm/i915: Read eDP Display control capability registers

[Yetunde Adebisi]

Add new edp_dpcd variable to intel_dp.
Read and save eDP Display control capability registers to edp_dpcd.

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c  | 15 ++++++++++-----
 drivers/gpu/drm/i915/intel_drv.h |  1 +
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index f192f58..c12c414 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3714,7 +3714,6 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
 	struct drm_device *dev = dig_port->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	uint8_t rev;
 
 	if (drm_dp_dpcd_read(&intel_dp->aux, 0x000, intel_dp->dpcd,
 			     sizeof(intel_dp->dpcd)) < 0)
@@ -3771,6 +3770,15 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 			DRM_DEBUG_KMS("PSR2 %s on sink",
 				dev_priv->psr.psr2_support ? "supported" : "not supported");
 		}
+
+		/* Read the eDP Display control capabilities registers */
+		memset(intel_dp->edp_dpcd, 0, sizeof(intel_dp->edp_dpcd));
+		if ((intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
+				(drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV,
+						intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
+								sizeof(intel_dp->edp_dpcd)))
+			DRM_DEBUG_KMS("EDP DPCD : %*ph\n", (int) sizeof(intel_dp->edp_dpcd),
+					intel_dp->edp_dpcd);
 	}
 
 	DRM_DEBUG_KMS("Display Port TPS3 support: source %s, sink %s\n",
@@ -3778,10 +3786,7 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 		      yesno(drm_dp_tps3_supported(intel_dp->dpcd)));
 
 	/* Intermediate frequency support */
-	if (is_edp(intel_dp) &&
-	    (intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] &	DP_DPCD_DISPLAY_CONTROL_CAPABLE) &&
-	    (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV, &rev, 1) == 1) &&
-	    (rev >= 0x03)) { /* eDp v1.4 or higher */
+	if (is_edp(intel_dp) && (intel_dp->edp_dpcd[0] >= 0x03)) { /* eDp v1.4 or higher */
 		__le16 sink_rates[DP_MAX_SUPPORTED_RATES];
 		int i;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index b9f1304..99db8bb 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -810,6 +810,7 @@ struct intel_dp {
 	uint8_t dpcd[DP_RECEIVER_CAP_SIZE];
 	uint8_t psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
 	uint8_t downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
+	uint8_t edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
 	/* sink rates as reported by DP_SUPPORTED_LINK_RATES */
 	uint8_t num_sink_rates;
 	int sink_rates[DP_MAX_SUPPORTED_RATES];
-- 
1.9.3

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[PATCH 3/3] drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

[Yetunde Adebisi]

This patch adds support for eDP backlight control using DPCD registers to
backlight hooks in intel_panel.

It checks for backlight control over AUX channel capability and sets up
function pointers to get and set the backlight brightness level if
supported.

v2: Moved backlight functions from intel_dp.c into a new file
intel_dp_aux_backlight.c. Also moved reading of eDP display control
registers to intel_dp_get_dpcd

v3: Correct some formatting mistakes

v4: Updated to use AUX backlight control if PWM control is not possible
	(Jani)
v5: Moved call to initialize backlight registers to dp_aux_setup_backlight
v6: Check DP_EDP_BACKLIGHT_PIN_ENABLE_CAP is disabled before setting up AUX
backlight control. To fix BLM_PWM_ENABLE igt test warnings on bdw_ultra
v7: Add enable_dpcd_backlight module parameter.
v8: Rebase onto latest drm-intel-nightly branch
v9: Remove references to intel_dp_dpcd_read_wake
    Split addition edp_dpcd variable into a separate patch

Cc: Bob Paauwe <bob.j.paauwe@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>
---
 drivers/gpu/drm/i915/Makefile                 |   1 +
 drivers/gpu/drm/i915/i915_params.c            |   4 +
 drivers/gpu/drm/i915/i915_params.h            |   1 +
 drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 173 ++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h              |   3 +
 drivers/gpu/drm/i915/intel_panel.c            |   4 +
 6 files changed, 186 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 0b88ba0..723c502 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -81,6 +81,7 @@ i915-y += dvo_ch7017.o \
 	  dvo_tfp410.o \
 	  intel_crt.o \
 	  intel_ddi.o \
+	  intel_dp_aux_backlight.o \
 	  intel_dp_link_training.o \
 	  intel_dp_mst.o \
 	  intel_dp.o \
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 1779f02..383c076 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -58,6 +58,7 @@ struct i915_params i915 __read_mostly = {
 	.guc_log_level = -1,
 	.enable_dp_mst = true,
 	.inject_load_failure = 0,
+	.enable_dpcd_backlight = false,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -210,3 +211,6 @@ MODULE_PARM_DESC(enable_dp_mst,
 module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
 MODULE_PARM_DESC(inject_load_failure,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
+module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
+MODULE_PARM_DESC(enable_dpcd_backlight,
+	"Enable support for DPCD backlight control (default:false)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 02bc278..65e73dd 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -61,6 +61,7 @@ struct i915_params {
 	bool verbose_state_checks;
 	bool nuclear_pageflip;
 	bool enable_dp_mst;
+	bool enable_dpcd_backlight;
 };
 
 extern struct i915_params i915 __read_mostly;
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
new file mode 100644
index 0000000..984fb0d
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -0,0 +1,173 @@
+/*
+ * 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.
+ *
+ */
+
+#include "intel_drv.h"
+
+static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
+{
+	uint8_t reg_val = 0;
+
+	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+			&reg_val) < 0) {
+		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+				DP_EDP_DISPLAY_CONTROL_REGISTER);
+		return;
+	}
+	if (enable)
+		reg_val |= DP_EDP_BACKLIGHT_ENABLE;
+	else
+		reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+			reg_val) != 1) {
+		DRM_DEBUG_KMS("Failed to %s aux backlight\n",
+				enable ? "enable" : "disable");
+	}
+}
+
+/*
+ * Read the current backlight value from DPCD register(s) based
+ * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
+ */
+static uint32_t intel_dp_aux_get_backlight(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t read_val[2] = { 0x0 };
+	uint16_t level = 0;
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+			&read_val, sizeof(read_val)) < 0) {
+		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+				DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
+		return 0;
+	}
+	level = read_val[0];
+	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+		level = (read_val[0] << 8 | read_val[1]);
+
+	return level;
+}
+
+/*
+ * Sends the current backlight level over the aux channel, checking if its using
+ * 8-bit or 16 bit value (MSB and LSB)
+ */
+static void
+intel_dp_aux_set_backlight(struct intel_connector *connector, u32 level)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t vals[2] = { 0x0 };
+
+	vals[0] = level;
+
+	/* Write the MSB and/or LSB */
+	 if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
+		vals[0] = (level & 0xFF00) >> 8;
+		vals[1] = (level & 0xFF);
+	}
+	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+			vals, sizeof(vals)) < 0) {
+		DRM_DEBUG_KMS("Failed to write aux backlight level\n");
+		return;
+	}
+}
+
+static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	uint8_t dpcd_buf = 0;
+
+	set_aux_backlight_enable(intel_dp, true);
+
+	if ((drm_dp_dpcd_readb(&intel_dp->aux,
+			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) == 1) &&
+			((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
+					DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
+		drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+				(dpcd_buf | DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
+}
+
+static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
+{
+	set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base), false);
+}
+
+static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
+			enum pipe pipe)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+	struct intel_panel *panel = &connector->panel;
+
+	intel_dp_aux_enable_backlight(connector);
+
+	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+		panel->backlight.max = 0xFFFF;
+	else
+		panel->backlight.max = 0xFF;
+
+	panel->backlight.min = 0;
+	panel->backlight.level = intel_dp_aux_get_backlight(connector);
+
+	panel->backlight.enabled = panel->backlight.level != 0;
+
+	return 0;
+}
+
+static bool
+intel_dp_aux_display_control_capable(struct intel_connector *connector)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+
+	/* Check the  eDP Display control capabilities registers to determine if
+	 * the panel can support backlight control over the aux channel
+	 */
+	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
+			(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
+			!((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
+					(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
+
+		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
+		return true;
+	}
+	return false;
+}
+
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+{
+	struct intel_panel *panel = &intel_connector->panel;
+
+	if(!i915.enable_dpcd_backlight)
+		return -ENODEV;
+
+	if (!intel_dp_aux_display_control_capable(intel_connector))
+		return -ENODEV;
+
+	panel->backlight.setup = intel_dp_aux_setup_backlight;
+	panel->backlight.enable = intel_dp_aux_enable_backlight;
+	panel->backlight.disable = intel_dp_aux_disable_backlight;
+	panel->backlight.set = intel_dp_aux_set_backlight;
+	panel->backlight.get = intel_dp_aux_get_backlight;
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 99db8bb..cb89a35 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1337,6 +1337,9 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
 bool
 intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
 
+/* intel_dp_aux_backlight.c */
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
+
 /* intel_dp_mst.c */
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index a078876..bd31481 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1718,6 +1718,10 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
 		container_of(panel, struct intel_connector, panel);
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
 
+	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
+			intel_dp_aux_init_backlight_funcs(connector) == 0)
+		return;
+
 	if (IS_BROXTON(dev_priv)) {
 		panel->backlight.setup = bxt_setup_backlight;
 		panel->backlight.enable = bxt_enable_backlight;
-- 
1.9.3

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Re: [PATCH 3/3] drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

[Daniel Vetter]

On Tue, Apr 26, 2016 at 12:25:18PM +0100, Yetunde Adebisi wrote:
> This patch adds support for eDP backlight control using DPCD registers to
> backlight hooks in intel_panel.
> 
> It checks for backlight control over AUX channel capability and sets up
> function pointers to get and set the backlight brightness level if
> supported.
> 
> v2: Moved backlight functions from intel_dp.c into a new file
> intel_dp_aux_backlight.c. Also moved reading of eDP display control
> registers to intel_dp_get_dpcd
> 
> v3: Correct some formatting mistakes
> 
> v4: Updated to use AUX backlight control if PWM control is not possible
> 	(Jani)
> v5: Moved call to initialize backlight registers to dp_aux_setup_backlight
> v6: Check DP_EDP_BACKLIGHT_PIN_ENABLE_CAP is disabled before setting up AUX
> backlight control. To fix BLM_PWM_ENABLE igt test warnings on bdw_ultra
> v7: Add enable_dpcd_backlight module parameter.
> v8: Rebase onto latest drm-intel-nightly branch
> v9: Remove references to intel_dp_dpcd_read_wake
>     Split addition edp_dpcd variable into a separate patch
> 
> Cc: Bob Paauwe <bob.j.paauwe@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>

Just a quick comment since I'm typing the regular changelog summaries: I
think the backlight driver in here would have been real nice as a generic
thing on top of the dp aux library. But ok if the next person gets to do
that, too ;-)
-Daniel

> ---
>  drivers/gpu/drm/i915/Makefile                 |   1 +
>  drivers/gpu/drm/i915/i915_params.c            |   4 +
>  drivers/gpu/drm/i915/i915_params.h            |   1 +
>  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 173 ++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h              |   3 +
>  drivers/gpu/drm/i915/intel_panel.c            |   4 +
>  6 files changed, 186 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 0b88ba0..723c502 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -81,6 +81,7 @@ i915-y += dvo_ch7017.o \
>  	  dvo_tfp410.o \
>  	  intel_crt.o \
>  	  intel_ddi.o \
> +	  intel_dp_aux_backlight.o \
>  	  intel_dp_link_training.o \
>  	  intel_dp_mst.o \
>  	  intel_dp.o \
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 1779f02..383c076 100644
> --- a/drivers/gpu/drm/i915/i915_params.c
> +++ b/drivers/gpu/drm/i915/i915_params.c
> @@ -58,6 +58,7 @@ struct i915_params i915 __read_mostly = {
>  	.guc_log_level = -1,
>  	.enable_dp_mst = true,
>  	.inject_load_failure = 0,
> +	.enable_dpcd_backlight = false,
>  };
>  
>  module_param_named(modeset, i915.modeset, int, 0400);
> @@ -210,3 +211,6 @@ MODULE_PARM_DESC(enable_dp_mst,
>  module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
>  MODULE_PARM_DESC(inject_load_failure,
>  	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
> +module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
> +MODULE_PARM_DESC(enable_dpcd_backlight,
> +	"Enable support for DPCD backlight control (default:false)");
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index 02bc278..65e73dd 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -61,6 +61,7 @@ struct i915_params {
>  	bool verbose_state_checks;
>  	bool nuclear_pageflip;
>  	bool enable_dp_mst;
> +	bool enable_dpcd_backlight;
>  };
>  
>  extern struct i915_params i915 __read_mostly;
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> new file mode 100644
> index 0000000..984fb0d
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -0,0 +1,173 @@
> +/*
> + * 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.
> + *
> + */
> +
> +#include "intel_drv.h"
> +
> +static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
> +{
> +	uint8_t reg_val = 0;
> +
> +	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
> +			&reg_val) < 0) {
> +		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +				DP_EDP_DISPLAY_CONTROL_REGISTER);
> +		return;
> +	}
> +	if (enable)
> +		reg_val |= DP_EDP_BACKLIGHT_ENABLE;
> +	else
> +		reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
> +
> +	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
> +			reg_val) != 1) {
> +		DRM_DEBUG_KMS("Failed to %s aux backlight\n",
> +				enable ? "enable" : "disable");
> +	}
> +}
> +
> +/*
> + * Read the current backlight value from DPCD register(s) based
> + * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
> + */
> +static uint32_t intel_dp_aux_get_backlight(struct intel_connector *connector)
> +{
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> +	uint8_t read_val[2] = { 0x0 };
> +	uint16_t level = 0;
> +
> +	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
> +			&read_val, sizeof(read_val)) < 0) {
> +		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
> +				DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
> +		return 0;
> +	}
> +	level = read_val[0];
> +	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
> +		level = (read_val[0] << 8 | read_val[1]);
> +
> +	return level;
> +}
> +
> +/*
> + * Sends the current backlight level over the aux channel, checking if its using
> + * 8-bit or 16 bit value (MSB and LSB)
> + */
> +static void
> +intel_dp_aux_set_backlight(struct intel_connector *connector, u32 level)
> +{
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> +	uint8_t vals[2] = { 0x0 };
> +
> +	vals[0] = level;
> +
> +	/* Write the MSB and/or LSB */
> +	 if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
> +		vals[0] = (level & 0xFF00) >> 8;
> +		vals[1] = (level & 0xFF);
> +	}
> +	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
> +			vals, sizeof(vals)) < 0) {
> +		DRM_DEBUG_KMS("Failed to write aux backlight level\n");
> +		return;
> +	}
> +}
> +
> +static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
> +{
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> +	uint8_t dpcd_buf = 0;
> +
> +	set_aux_backlight_enable(intel_dp, true);
> +
> +	if ((drm_dp_dpcd_readb(&intel_dp->aux,
> +			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) == 1) &&
> +			((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
> +					DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
> +		drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
> +				(dpcd_buf | DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
> +}
> +
> +static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
> +{
> +	set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base), false);
> +}
> +
> +static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
> +			enum pipe pipe)
> +{
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> +	struct intel_panel *panel = &connector->panel;
> +
> +	intel_dp_aux_enable_backlight(connector);
> +
> +	if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
> +		panel->backlight.max = 0xFFFF;
> +	else
> +		panel->backlight.max = 0xFF;
> +
> +	panel->backlight.min = 0;
> +	panel->backlight.level = intel_dp_aux_get_backlight(connector);
> +
> +	panel->backlight.enabled = panel->backlight.level != 0;
> +
> +	return 0;
> +}
> +
> +static bool
> +intel_dp_aux_display_control_capable(struct intel_connector *connector)
> +{
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
> +
> +	/* Check the  eDP Display control capabilities registers to determine if
> +	 * the panel can support backlight control over the aux channel
> +	 */
> +	if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
> +			(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
> +			!((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
> +					(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
> +
> +		DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
> +		return true;
> +	}
> +	return false;
> +}
> +
> +int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
> +{
> +	struct intel_panel *panel = &intel_connector->panel;
> +
> +	if(!i915.enable_dpcd_backlight)
> +		return -ENODEV;
> +
> +	if (!intel_dp_aux_display_control_capable(intel_connector))
> +		return -ENODEV;
> +
> +	panel->backlight.setup = intel_dp_aux_setup_backlight;
> +	panel->backlight.enable = intel_dp_aux_enable_backlight;
> +	panel->backlight.disable = intel_dp_aux_disable_backlight;
> +	panel->backlight.set = intel_dp_aux_set_backlight;
> +	panel->backlight.get = intel_dp_aux_get_backlight;
> +
> +	return 0;
> +}
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 99db8bb..cb89a35 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1337,6 +1337,9 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
>  bool
>  intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
>  
> +/* intel_dp_aux_backlight.c */
> +int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
> +
>  /* intel_dp_mst.c */
>  int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
>  void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index a078876..bd31481 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -1718,6 +1718,10 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
>  		container_of(panel, struct intel_connector, panel);
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  
> +	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
> +			intel_dp_aux_init_backlight_funcs(connector) == 0)
> +		return;
> +
>  	if (IS_BROXTON(dev_priv)) {
>  		panel->backlight.setup = bxt_setup_backlight;
>  		panel->backlight.enable = bxt_enable_backlight;
> -- 
> 1.9.3
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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