gma500: Sort out dither

Ubuntu users reported that dithering was not being set on Poulsbo, and they
have a point as we set one variable and check another which is never set.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Tested-by: Luca Forina <luca.forina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/gma500/cdv_intel_lvds.c

@@ -356,6 +356,7 @@ static void cdv_intel_lvds_mode_set(struct drm_encoder *encoder,
 	struct psb_intel_mode_device *mode_dev =
 	    enc_to_psb_intel_output(encoder)->mode_dev;
 	struct drm_device *dev = encoder->dev;
+	struct drm_psb_private *dev_priv = dev->dev_private;
 	u32 pfit_control;
 
 	/*
@@ -377,7 +378,7 @@ static void cdv_intel_lvds_mode_set(struct drm_encoder *encoder,
 	else
 		pfit_control = 0;
 
-	if (mode_dev->panel_wants_dither)
+	if (dev_priv->lvds_dither)
 		pfit_control |= PANEL_8TO6_DITHER_ENABLE;
 
 	REG_WRITE(PFIT_CONTROL, pfit_control);

drivers/staging/gma500/mrst_lvds.c

@@ -91,6 +91,7 @@ static void mrst_lvds_mode_set(struct drm_encoder *encoder,
 	struct psb_intel_mode_device *mode_dev =
 				enc_to_psb_intel_output(encoder)->mode_dev;
 	struct drm_device *dev = encoder->dev;
+	struct drm_psb_private *dev_priv = dev->dev_private;
 	u32 lvds_port;
 	uint64_t v = DRM_MODE_SCALE_FULLSCREEN;
 
@@ -107,7 +108,9 @@ static void mrst_lvds_mode_set(struct drm_encoder *encoder,
 		    LVDS_PORT_EN |
 		    LVDS_BORDER_EN;
 
-	if (mode_dev->panel_wants_dither)
+	/* If the firmware says dither on Moorestown, or the BIOS does
+	   on Oaktrail then enable dithering */
+	if (mode_dev->panel_wants_dither || dev_priv->lvds_dither)
 		lvds_port |= MRST_PANEL_8TO6_DITHER_ENABLE;
 
 	REG_WRITE(LVDS, lvds_port);

drivers/staging/gma500/psb_intel_lvds.c

@@ -470,6 +470,7 @@ static void psb_intel_lvds_mode_set(struct drm_encoder *encoder,
 	struct psb_intel_mode_device *mode_dev =
 	    enc_to_psb_intel_output(encoder)->mode_dev;
 	struct drm_device *dev = encoder->dev;
+	struct drm_psb_private *dev_priv = dev->dev_private;
 	u32 pfit_control;
 
 	/*
@@ -491,7 +492,7 @@ static void psb_intel_lvds_mode_set(struct drm_encoder *encoder,
 	else
 		pfit_control = 0;
 
-	if (mode_dev->panel_wants_dither)
+	if (dev_priv->lvds_dither)
 		pfit_control |= PANEL_8TO6_DITHER_ENABLE;
 
 	REG_WRITE(PFIT_CONTROL, pfit_control);