drm/i915/lvds: Restore dithering on native modes for gen2/3

A regression introduced in bee17e5 cleared the dithering bit for native
modes on gen2/3.

Bugzilla: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/711568
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index ace8d5d30dd21b25b3f0390cdd2b8d13659f666e..bcdba7bd5cfafb26efa1b8f150530836d8cc5c71 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -261,12 +261,6 @@ static bool intel_lvds_mode_fixup(struct drm_encoder *encoder,
                return true;
        }
 
-       /* Make sure pre-965s set dither correctly */
-       if (INTEL_INFO(dev)->gen < 4) {
-               if (dev_priv->lvds_dither)
-                       pfit_control |= PANEL_8TO6_DITHER_ENABLE;
-       }
-
        /* Native modes don't need fitting */
        if (adjusted_mode->hdisplay == mode->hdisplay &&
            adjusted_mode->vdisplay == mode->vdisplay)
@@ -374,10 +368,16 @@ static bool intel_lvds_mode_fixup(struct drm_encoder *encoder,
        }
 
 out:
+       /* If not enabling scaling, be consistent and always use 0. */
        if ((pfit_control & PFIT_ENABLE) == 0) {
                pfit_control = 0;
                pfit_pgm_ratios = 0;
        }
+
+       /* Make sure pre-965 set dither correctly */
+       if (INTEL_INFO(dev)->gen < 4 && dev_priv->lvds_dither)
+               pfit_control |= PANEL_8TO6_DITHER_ENABLE;
+
        if (pfit_control != intel_lvds->pfit_control ||
            pfit_pgm_ratios != intel_lvds->pfit_pgm_ratios) {
                intel_lvds->pfit_control = pfit_control;