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author | Imre Deak <imre.deak@intel.com> | 2015-08-14 18:43:30 +0300 |
---|---|---|
committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2015-08-26 10:39:14 +0300 |
commit | e5756c10d841ddb448293c849392f3d6b809561f (patch) | |
tree | 4a8d82055d6736a0d76fe04e18334156466faa62 /drivers/gpu/drm/i915/i915_gem.c | |
parent | 319404df2f682ddabf98cbf6421bb43b951ca978 (diff) | |
download | linux-e5756c10d841ddb448293c849392f3d6b809561f.tar.xz |
drm/i915/bxt: don't allow cached GEM mappings on A stepping
Due to a coherency issue on BXT A steppings we can't guarantee a
coherent view of cached (CPU snooped) GPU mappings, so fail such
requests. User space is supposed to fall back to uncached mappings in
this case.
v2:
- limit the WA to A steppings, on later stepping this HW issue is fixed
v3:
- return error instead of trying to work around the issue in kernel,
since that could confuse user space (Chris)
Testcast: igt/gem_store_dword_batches_loop/cached-mapping
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem.c')
-rw-r--r-- | drivers/gpu/drm/i915/i915_gem.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 1ac57ec803bd..41263cd4170c 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3742,6 +3742,15 @@ int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data, level = I915_CACHE_NONE; break; case I915_CACHING_CACHED: + /* + * Due to a HW issue on BXT A stepping, GPU stores via a + * snooped mapping may leave stale data in a corresponding CPU + * cacheline, whereas normally such cachelines would get + * invalidated. + */ + if (IS_BROXTON(dev) && INTEL_REVID(dev) < BXT_REVID_B0) + return -ENODEV; + level = I915_CACHE_LLC; break; case I915_CACHING_DISPLAY: |