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78 lines
2.6 KiB
78 lines
2.6 KiB
From 9286a0bc63de32c66d894b45dcf048a072a84cd7 Mon Sep 17 00:00:00 2001
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From: Adam Jackson <ajax@redhat.com>
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Date: Mon, 19 Apr 2010 15:57:25 -0400
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Subject: [PATCH 1/4] drm/i915: Use spatio-temporal dithering on PCH
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Spatial dither is better than nothing, but ST is even better.
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(from ajax's followup message:)
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I noticed this with:
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http://ajax.fedorapeople.org/YellowFlower.jpg
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set as my desktop background in Gnome on a 1280x800 machine (in
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particular, a Sony Vaio VPCB1 with 6-bit panel and a rather bright black
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level). Easiest way to test this is by poking at PIPEACONF with
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intel_reg_write directly:
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% sudo intel_reg_write 0x70008 0xc0000040 # no dither
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% sudo intel_reg_write 0x70008 0xc0000050 # spatial
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% sudo intel_reg_write 0x70008 0xc0000054 # ST
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I notice it especially strongly in the relatively flat dark area in the
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top left. Closer than about 18" I can see a noticeable checkerboard
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pattern with plain spatial dithering. ST smooths that out; I can still
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tell that it's lacking color precision, but it's not offensive.
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Signed-off-by: Adam Jackson <ajax@redhat.com>
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Signed-off-by: Eric Anholt <eric@anholt.net>
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---
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drivers/gpu/drm/i915/i915_reg.h | 5 ++++-
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drivers/gpu/drm/i915/intel_display.c | 10 ++++++----
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2 files changed, 10 insertions(+), 5 deletions(-)
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diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
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index 4cbc521..89b6efc 100644
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--- a/drivers/gpu/drm/i915/i915_reg.h
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+++ b/drivers/gpu/drm/i915/i915_reg.h
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@@ -1924,7 +1924,10 @@
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/* Display & cursor control */
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/* dithering flag on Ironlake */
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-#define PIPE_ENABLE_DITHER (1 << 4)
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+#define PIPE_ENABLE_DITHER (1 << 4)
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+#define PIPE_DITHER_TYPE_MASK (3 << 2)
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+#define PIPE_DITHER_TYPE_SPATIAL (0 << 2)
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+#define PIPE_DITHER_TYPE_ST01 (1 << 2)
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/* Pipe A */
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#define PIPEADSL 0x70000
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#define PIPEACONF 0x70008
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diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
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index c7502b6..f1a37d9 100644
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--- a/drivers/gpu/drm/i915/intel_display.c
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+++ b/drivers/gpu/drm/i915/intel_display.c
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@@ -3321,14 +3321,16 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
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/* set the dithering flag */
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if (IS_I965G(dev)) {
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if (dev_priv->lvds_dither) {
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- if (HAS_PCH_SPLIT(dev))
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+ if (HAS_PCH_SPLIT(dev)) {
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pipeconf |= PIPE_ENABLE_DITHER;
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- else
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+ pipeconf |= PIPE_DITHER_TYPE_ST01;
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+ } else
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lvds |= LVDS_ENABLE_DITHER;
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} else {
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- if (HAS_PCH_SPLIT(dev))
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+ if (HAS_PCH_SPLIT(dev)) {
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pipeconf &= ~PIPE_ENABLE_DITHER;
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- else
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+ pipeconf &= ~PIPE_DITHER_TYPE_MASK;
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+ } else
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lvds &= ~LVDS_ENABLE_DITHER;
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}
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}
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--
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1.7.0.1
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