From 651d794fae9b79237aae1c97f8a9d9f3817bd31d Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 8 Aug 2013 14:41:10 +0100 Subject: drm/i915: Use Write-Through cacheing for the display plane on Iris MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Haswell GT3e has the unique feature of supporting Write-Through cacheing of objects within the eLLC/LLC. The purpose of this is to enable the display plane to remain coherent whilst objects lie resident in the eLLC/LLC - so that we, in theory, get the best of both worlds, perfect display and fast access. However, we still need to be careful as the CPU does not see the WT when accessing the cache. In particular, this means that we need to flush the cache lines after writing to an object through the CPU, and on transitioning from a cached state to WT. v2: Actually do the clflush on transition to WT, nagging by Ville. v3: Flush the CPU cache after writes into WT objects. v4: Rease onto LLC updates and report WT as "uncached" for get_cache_level_ioctl to remain symmetric with set_cache_level_ioctl. Signed-off-by: Chris Wilson Cc: Ville Syrjälä Cc: Kenneth Graunke Reviewed-by: Ville Syrjälä Signed-off-by: Daniel Vetter --- include/uapi/drm/i915_drm.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi/drm') diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index 0bb3e5524382..55bb5729bd78 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -334,6 +334,7 @@ typedef struct drm_i915_irq_wait { #define I915_PARAM_HAS_PINNED_BATCHES 24 #define I915_PARAM_HAS_EXEC_NO_RELOC 25 #define I915_PARAM_HAS_EXEC_HANDLE_LUT 26 +#define I915_PARAM_HAS_WT 27 typedef struct drm_i915_getparam { int param; -- cgit v1.2.2