This patch enables support for DPCD backlight control for DP connectors.
The VESA spec defines DPCD backlight control only for eDP but some add-on
cards like the Chrontel CH7511B DP-LVDS cards have the display control
DPCD registers enabled.
This patch registers a backlight device exposed via sysfs that controls the
connected panel backlight by writing to DPCD registers on the CH7511B
add-on card
Signed-off-by: Yetunde Adebisi <yetundex.adeb...@intel.com>
---
drivers/gpu/drm/i915/intel_dp.c | 25 ++++++++++++++++++++
drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 7 ++++++
drivers/gpu/drm/i915/intel_drv.h | 2 ++
drivers/gpu/drm/i915/intel_panel.c | 33 +++++++++++++++++++--------
4 files changed, 57 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 9e9e7f1..8bbfb7f 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5631,6 +5631,30 @@ intel_dp_drrs_init(struct intel_connector
*intel_connector,
return downclock_mode;
}
+/*
+ * Called on DP connector initialization to check for aux backlight control
+ * capability on the sink device and if present, initialize it.
+ */
+static void intel_dp_init_aux_backlight(struct intel_dp *intel_dp,
+ struct drm_connector *connector)
+{
+ struct intel_connector *intel_connector = to_intel_connector(connector);
+
+ if (is_edp(intel_dp))
+ return;
+
+ if (i915.enable_dpcd_backlight &&
+ (intel_dp_dpcd_read_wake(&intel_dp->aux,
DP_EDP_DPCD_REV,
+ intel_dp->edp_dpcd,
sizeof(intel_dp->edp_dpcd)) ==
+
sizeof(intel_dp->edp_dpcd)) &&
+
intel_dp_aux_init_backlight_funcs(intel_connector) == 0) {
+ intel_panel_setup_backlight(connector, INVALID_PIPE);
+
+ intel_connector->panel.backlight.power =
intel_dp_aux_backlight_power;
+ intel_connector->panel.backlight.enabled = true;
+ }
+}
+
static bool intel_edp_init_connector(struct intel_dp *intel_dp,
struct intel_connector *intel_connector)
{
@@ -5868,6 +5892,7 @@ intel_dp_init_connector(struct intel_digital_port
*intel_dig_port,
goto fail;
}
+ intel_dp_init_aux_backlight(intel_dp, connector);
intel_dp_add_properties(intel_dp, connector);
/* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
index a5361d6..efa657f 100644
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -168,3 +168,10 @@ int intel_dp_aux_init_backlight_funcs(struct
intel_connector *intel_connector)
return 0;
}
+
+void intel_dp_aux_backlight_power(struct intel_connector *connector,
+ bool enable)
+{
+ set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base),
+ enable);
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 782a103..ab92e89 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1324,6 +1324,8 @@ ssize_t intel_dp_dpcd_read_wake(struct drm_dp_aux *aux,
unsigned int offset,
/* intel_dp_aux_backlight.c */
int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
+void intel_dp_aux_backlight_power(struct intel_connector *connector,
+ bool enable);
/* intel_dp_mst.c */
int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int
conn_id);
diff --git a/drivers/gpu/drm/i915/intel_panel.c
b/drivers/gpu/drm/i915/intel_panel.c
index cdfcdad..d678e55 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1193,16 +1193,29 @@ static int intel_backlight_device_register(struct
intel_connector *connector)
else
props.power = FB_BLANK_POWERDOWN;
- /*
- * Note: using the same name independent of the connector prevents
- * registration of multiple backlight devices in the driver.
- */
- panel->backlight.device =
- backlight_device_register("intel_backlight",
- connector->base.kdev,
- connector,
- &intel_backlight_device_ops, &props);
-
+ if (connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
+ char *name = kasprintf(GFP_KERNEL, "intel_aux_backlight-%s",
+ connector->base.name);
+ if (!name)
+ return -ENOMEM;
+
+ panel->backlight.device =
+ backlight_device_register(name,
+ connector->base.kdev,
+ connector,
+ &intel_backlight_device_ops,
&props);
+ kfree(name);
+ } else {
+ /*
+ * Note: using the same name independent of the connector
prevents
+ * registration of multiple backlight devices in the driver.
+ */
+ panel->backlight.device =
+ backlight_device_register("intel_backlight",
+ connector->base.kdev,
+ connector,
+ &intel_backlight_device_ops,
&props);
+ }
if (IS_ERR(panel->backlight.device)) {
DRM_ERROR("Failed to register backlight: %ld\n",
PTR_ERR(panel->backlight.device));
--
1.9.3
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