[PATCH] properly enable the blc controller on the right pipe

[daniel.vetter at ffwll.ch (Daniel Vetter)]

Depending upon how things are set up, this might help. If not, please
install intel-gpu-tools and grab the output of intel_reg_dumper both
when booting with nomodeset and when booting with kms.

Thanks, Daniel
---
 drivers/gpu/drm/i915/intel_drv.h   |    3 ++-
 drivers/gpu/drm/i915/intel_lvds.c  |    3 ++-
 drivers/gpu/drm/i915/intel_panel.c |   15 ++++++++++++++-
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 715afa1..5a021ce 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -323,7 +323,8 @@ extern u32 intel_panel_get_max_backlight(struct drm_device *dev);
 extern u32 intel_panel_get_backlight(struct drm_device *dev);
 extern void intel_panel_set_backlight(struct drm_device *dev, u32 level);
 extern int intel_panel_setup_backlight(struct drm_device *dev);
-extern void intel_panel_enable_backlight(struct drm_device *dev);
+extern void intel_panel_enable_backlight(struct drm_device *dev,
+					 enum pipe pipe);
 extern void intel_panel_disable_backlight(struct drm_device *dev);
 extern void intel_panel_destroy_backlight(struct drm_device *dev);
 extern enum drm_connector_status intel_panel_detect(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 30e2c82..3e71b86 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -71,6 +71,7 @@ static struct intel_lvds *intel_attached_lvds(struct drm_connector *connector)
 static void intel_lvds_enable(struct intel_lvds *intel_lvds)
 {
 	struct drm_device *dev = intel_lvds->base.base.dev;
+	struct intel_crtc *intel_crtc = to_intel_crtc(intel_lvds->base.base.crtc);
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 ctl_reg, lvds_reg, stat_reg;
 
@@ -107,7 +108,7 @@ static void intel_lvds_enable(struct intel_lvds *intel_lvds)
 	if (wait_for((I915_READ(stat_reg) & PP_ON) != 0, 1000))
 		DRM_ERROR("timed out waiting for panel to power on\n");
 
-	intel_panel_enable_backlight(dev);
+	intel_panel_enable_backlight(dev, intel_crtc->pipe);
 }
 
 static void intel_lvds_disable(struct intel_lvds *intel_lvds)
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 48177ec..486cf92 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -261,17 +261,30 @@ void intel_panel_disable_backlight(struct drm_device *dev)
 
 	dev_priv->backlight_enabled = false;
 	intel_panel_actually_set_backlight(dev, 0);
+
+	/*disable the blc*/
+	I915_WRITE(BLC_PWM_CTL2,
+		   I915_READ(BLC_PWM_CTL2) & ~(1<<31));
 }
 
-void intel_panel_enable_backlight(struct drm_device *dev)
+void intel_panel_enable_backlight(struct drm_device *dev,
+				  enum pipe pipe)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 tmp;
 
 	if (dev_priv->backlight_level == 0)
 		dev_priv->backlight_level = intel_panel_get_max_backlight(dev);
 
 	dev_priv->backlight_enabled = true;
 	intel_panel_actually_set_backlight(dev, dev_priv->backlight_level);
+
+	/*enable the blc on the right pipe*/
+	tmp = I915_READ(BLC_PWM_CTL2);
+	tmp &= ~(1<<29); /* pipe select */
+	tmp |= pipe == PIPE_A ? 0 : 1;
+	I915_WRITE(BLC_PWM_CTL2,
+		   I915_READ(BLC_PWM_CTL2) & ~(1<<31));
 }
 
 static void intel_panel_init_backlight(struct drm_device *dev)
-- 
1.7.10