drm/i915: Mark CPU cache as dirty on every transition for CPU writes
Currently, we only mark the CPU cache as dirty if we skip a clflush. This leads to some confusion where we have to ask if the object is in the write domain or missed a clflush. If we always mark the cache as dirty, this becomes a much simply question to answer. The goal remains to do as few clflushes as required and to do them as late as possible, in the hope of deferring the work to a kthread and not block the caller (e.g. execbuf, flips). v2: Always call clflush before GPU execution when the cache_dirty flag is set. This may cause some extra work on llc systems that migrate dirty buffers back and forth - but we do try to limit that by only setting cache_dirty at the end of the gpu sequence. v3: Always mark the cache as dirty upon a level change, as we need to invalidate any stale cachelines due to external writes. Reported-by:Dongwon Kim <dongwon.kim@intel.com> Fixes: a6a7cc4b ("drm/i915: Always flush the dirty CPU cache when pinning the scanout") Signed-off-by:
Chris Wilson <chris@chris-wilson.co.uk> Cc: Dongwon Kim <dongwon.kim@intel.com> Cc: Matt Roper <matthew.d.roper@intel.com> Tested-by:
Dongwon Kim <dongwon.kim@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170615123850.26843-1-chris@chris-wilson.co.ukReviewed-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com>
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