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>
diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 2e8ddfc..6318828 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -72,14 +72,16 @@
 {
 	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 @@
 		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 @@
 {
 	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;
 	}