3 files changed, 45 insertions, 28 deletions

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index c35edd7ca84d..1a1fdb088dda 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -379,7 +379,8 @@ 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 a7269e6b4bf7..492db7740de2 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)
@@ -1074,35 +1075,14 @@ bool intel_lvds_init(struct drm_device *dev)
 		goto failed;
 
 out:
+	/*
+	 * Unlock registers and just
+	 * leave them unlocked
+	 */
 	if (HAS_PCH_SPLIT(dev)) {
-		u32 pwm;
-
-		pipe = (I915_READ(PCH_LVDS) & LVDS_PIPEB_SELECT) ? 1 : 0;
-
-		/* make sure PWM is enabled and locked to the LVDS pipe */
-		pwm = I915_READ(BLC_PWM_CPU_CTL2);
-		if (pipe == 0 && (pwm & BLM_PIPE_B))
-			I915_WRITE(BLC_PWM_CPU_CTL2, pwm & ~BLM_PWM_ENABLE);
-		if (pipe)
-			pwm |= BLM_PIPE_B;
-		else
-			pwm &= ~BLM_PIPE_B;
-		I915_WRITE(BLC_PWM_CPU_CTL2, pwm | BLM_PWM_ENABLE);
-
-		pwm = I915_READ(BLC_PWM_PCH_CTL1);
-		pwm |= BLM_PCH_PWM_ENABLE;
-		I915_WRITE(BLC_PWM_PCH_CTL1, pwm);
-		/*
-		 * Unlock registers and just
-		 * leave them unlocked
-		 */
 		I915_WRITE(PCH_PP_CONTROL,
 			   I915_READ(PCH_PP_CONTROL) | PANEL_UNLOCK_REGS);
 	} else {
-		/*
-		 * Unlock registers and just
-		 * leave them unlocked
-		 */
 		I915_WRITE(PP_CONTROL,
 			   I915_READ(PP_CONTROL) | PANEL_UNLOCK_REGS);
 	}
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 7180cc828f94..58c7ee7238b8 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -287,9 +287,18 @@ void intel_panel_disable_backlight(struct drm_device *dev)
 
 	dev_priv->backlight_enabled = false;
 	intel_panel_actually_set_backlight(dev, 0);
+
+	if (INTEL_INFO(dev)->gen >= 4) {
+		uint32_t reg;
+
+		reg = HAS_PCH_SPLIT(dev) ? BLC_PWM_CPU_CTL2 : BLC_PWM_CTL2;
+
+		I915_WRITE(reg, I915_READ(reg) & ~BLM_PWM_ENABLE);
+	}
 }
 
-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;
 
@@ -298,6 +307,33 @@ void intel_panel_enable_backlight(struct drm_device *dev)
 
 	dev_priv->backlight_enabled = true;
 	intel_panel_actually_set_backlight(dev, dev_priv->backlight_level);
+
+	if (INTEL_INFO(dev)->gen >= 4) {
+		uint32_t reg, tmp;
+
+		reg = HAS_PCH_SPLIT(dev) ? BLC_PWM_CPU_CTL2 : BLC_PWM_CTL2;
+
+
+		tmp = I915_READ(reg);
+
+		/* Note that this can also get called through dpms changes. And
+		 * we don't track the backlight dpms state, hence check whether
+		 * we have to do anything first. */
+		if (tmp & BLM_PWM_ENABLE)
+			return;
+
+		if (dev_priv->num_pipe == 3)
+			tmp &= ~BLM_PIPE_SELECT_IVB;
+		else
+			tmp &= ~BLM_PIPE_SELECT;
+
+		tmp |= BLM_PIPE(pipe);
+		tmp &= ~BLM_PWM_ENABLE;
+
+		I915_WRITE(reg, tmp);
+		POSTING_READ(reg);
+		I915_WRITE(reg, tmp | BLM_PWM_ENABLE);
+	}
 }
 
 static void intel_panel_init_backlight(struct drm_device *dev)