drm/i915: Wait for LVDS panel power sequence

During mode setting, check to make sure the panel power sequencing has
completed before doing further operations on the device. This
uncovered errors with DPMS not turning the device off as it was left locked.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/gpu/drm/i915/intel_lvds.c

@@ -72,14 +72,16 @@ static void intel_lvds_enable(struct intel_lvds *intel_lvds)
 {
 	struct drm_device *dev = intel_lvds->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 ctl_reg, lvds_reg;
+	u32 ctl_reg, lvds_reg, stat_reg;
 
 	if (HAS_PCH_SPLIT(dev)) {
 		ctl_reg = PCH_PP_CONTROL;
 		lvds_reg = PCH_LVDS;
+		stat_reg = PCH_PP_STATUS;
 	} else {
 		ctl_reg = PP_CONTROL;
 		lvds_reg = LVDS;
+		stat_reg = PP_STATUS;
 	}
 
 	I915_WRITE(lvds_reg, I915_READ(lvds_reg) | LVDS_PORT_EN);
@@ -94,17 +96,16 @@ static void intel_lvds_enable(struct intel_lvds *intel_lvds)
 		DRM_DEBUG_KMS("applying panel-fitter: %x, %x\n",
 			      intel_lvds->pfit_control,
 			      intel_lvds->pfit_pgm_ratios);
-		if (wait_for((I915_READ(PP_STATUS) & PP_ON) == 0, 1000)) {
-			DRM_ERROR("timed out waiting for panel to power off\n");
-		} else {
-			I915_WRITE(PFIT_PGM_RATIOS, intel_lvds->pfit_pgm_ratios);
-			I915_WRITE(PFIT_CONTROL, intel_lvds->pfit_control);
-			intel_lvds->pfit_dirty = false;
-		}
+
+		I915_WRITE(PFIT_PGM_RATIOS, intel_lvds->pfit_pgm_ratios);
+		I915_WRITE(PFIT_CONTROL, intel_lvds->pfit_control);
+		intel_lvds->pfit_dirty = false;
 	}
 
 	I915_WRITE(ctl_reg, I915_READ(ctl_reg) | POWER_TARGET_ON);
 	POSTING_READ(lvds_reg);
+	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);
 }
@@ -113,24 +114,25 @@ static void intel_lvds_disable(struct intel_lvds *intel_lvds)
 {
 	struct drm_device *dev = intel_lvds->base.base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 ctl_reg, lvds_reg;
+	u32 ctl_reg, lvds_reg, stat_reg;
 
 	if (HAS_PCH_SPLIT(dev)) {
 		ctl_reg = PCH_PP_CONTROL;
 		lvds_reg = PCH_LVDS;
+		stat_reg = PCH_PP_STATUS;
 	} else {
 		ctl_reg = PP_CONTROL;
 		lvds_reg = LVDS;
+		stat_reg = PP_STATUS;
 	}
 
 	intel_panel_disable_backlight(dev);
 
 	I915_WRITE(ctl_reg, I915_READ(ctl_reg) & ~POWER_TARGET_ON);
+	if (wait_for((I915_READ(stat_reg) & PP_ON) == 0, 1000))
+		DRM_ERROR("timed out waiting for panel to power off\n");
 
 	if (intel_lvds->pfit_control) {
-		if (wait_for((I915_READ(PP_STATUS) & PP_ON) == 0, 1000))
-			DRM_ERROR("timed out waiting for panel to power off\n");
-
 		I915_WRITE(PFIT_CONTROL, 0);
 		intel_lvds->pfit_dirty = true;
 	}