drm/i915: framebuffer compression for pre-GM45
This patch adds framebuffer compression (good for about ~0.5W power
savings in the best case) support for pre-GM45 chips. GM45+ have a new,
more flexible FBC scheme that will be added in a separate patch.
FBC can't always be enabled: the compressed buffer must be physically
contiguous and reside in stolen space. So if you have a large display
and a small amount of stolen memory, you may not be able to take
advantage of FBC. In some cases, a BIOS setting controls how much
stolen space is available. Increasing this to 8 or 16M can help.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e38cd21..f7c2de8 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -343,6 +343,7 @@
#define FBC_CTL_PLANEA (0<<0)
#define FBC_CTL_PLANEB (1<<0)
#define FBC_FENCE_OFF 0x0321b
+#define FBC_TAG 0x03300
#define FBC_LL_SIZE (1536)