From b44ee8a479c3adb22b818b8b6aff29c6a08c1cb1 Mon Sep 17 00:00:00 2001
From: Adam Jackson <ajax@redhat.com>
Date: Mon, 19 Apr 2010 15:52:32 -0400
Subject: [PATCH] drm/i915: Use spatio-temporal dithering on PCH
Spatial dither is better than nothing, but ST is even better.
Signed-off-by: Adam Jackson <ajax@redhat.com>
---
drivers/gpu/drm/i915/i915_reg.h | 5 ++++-
drivers/gpu/drm/i915/intel_display.c | 10 ++++++----
2 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 527d30a..0bbbb77 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1922,7 +1922,10 @@
/* Display & cursor control */
/* dithering flag on Ironlake */
-#define PIPE_ENABLE_DITHER (1 << 4)
+#define PIPE_ENABLE_DITHER (1 << 4)
+#define PIPE_DITHER_TYPE_MASK (3 << 2)
+#define PIPE_DITHER_TYPE_SPATIAL (0 << 2)
+#define PIPE_DITHER_TYPE_ST01 (1 << 2)
/* Pipe A */
#define PIPEADSL 0x70000
#define PIPEACONF 0x70008
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 58668c4..36ead0e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3676,14 +3676,16 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
/* set the dithering flag */
if (IS_I965G(dev)) {
if (dev_priv->lvds_dither) {
- if (HAS_PCH_SPLIT(dev))
+ if (HAS_PCH_SPLIT(dev)) {
pipeconf |= PIPE_ENABLE_DITHER;
- else
+ pipeconf |= PIPE_DITHER_TYPE_ST01;
+ } else
lvds |= LVDS_ENABLE_DITHER;
} else {
- if (HAS_PCH_SPLIT(dev))
+ if (HAS_PCH_SPLIT(dev)) {
pipeconf &= ~PIPE_ENABLE_DITHER;
- else
+ pipeconf &= ~PIPE_DITHER_TYPE_MASK;
+ } else
lvds &= ~LVDS_ENABLE_DITHER;
}
}
--
1.7.0.1