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| author | Adam Jackson <ajax@redhat.com> | 2010-04-19 15:57:25 -0400 |
|---|---|---|
| committer | Eric Anholt <eric@anholt.net> | 2010-05-07 13:59:26 -0700 |
| commit | 0a31a448659d48cbc38f5e7520d8a65f8f1f8276 (patch) | |
| tree | d02870a48aaf5669a95906948bdfbc175bad45f1 | |
| parent | 9e51159c14c29ebd485a45ba56f148e180d62c29 (diff) | |
| download | linux-stable-0a31a448659d48cbc38f5e7520d8a65f8f1f8276.tar.gz linux-stable-0a31a448659d48cbc38f5e7520d8a65f8f1f8276.tar.bz2 linux-stable-0a31a448659d48cbc38f5e7520d8a65f8f1f8276.zip | |
drm/i915: Use spatio-temporal dithering on PCH
Spatial dither is better than nothing, but ST is even better.
(from ajax's followup message:)
I noticed this with:
http://ajax.fedorapeople.org/YellowFlower.jpg
set as my desktop background in Gnome on a 1280x800 machine (in
particular, a Sony Vaio VPCB1 with 6-bit panel and a rather bright black
level). Easiest way to test this is by poking at PIPEACONF with
intel_reg_write directly:
% sudo intel_reg_write 0x70008 0xc0000040 # no dither
% sudo intel_reg_write 0x70008 0xc0000050 # spatial
% sudo intel_reg_write 0x70008 0xc0000054 # ST
I notice it especially strongly in the relatively flat dark area in the
top left. Closer than about 18" I can see a noticeable checkerboard
pattern with plain spatial dithering. ST smooths that out; I can still
tell that it's lacking color precision, but it's not offensive.
Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
| -rw-r--r-- | drivers/gpu/drm/i915/i915_reg.h | 5 | ||||
| -rw-r--r-- | 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 527d30aecda2..0bbbb7753950 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 3836f56e842c..119a41ac3bb6 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -3677,14 +3677,16 @@ 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; } } |