[Intel-gfx] [PATCH] drm/i915: optimize the shmem_pwrite slowpath handling

[Chris Wilson]

On Thu, 15 Nov 2012 16:53:58 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> Since we drop dev->struct_mutex when going through the slowpath, the
> object might have been moved out of the cpu domain. Hence we need to
> clflush the entire object to ensure that after the ioctl returns,
> everything is coherent again (interwoven writes are ill-defined
> anyway).
> 
> But we only need to do this if we start in the cpu domain and the
> object requires flushing for coherency. So don't do the flushing if
> the object is coherent anyway or if we've done in-line clfushing
> already.
> 
> v2: i915_gem_clflush_object already checks whether the object is
> coherent and if so, drops the flushing. Hence we don't need to check
> that ourselves, simplifying the condition.
> 
> v3: Reorder the checks for better clarify (and adjust the comment
> accordingly), suggested by Chris Wilson.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Yup, the comment makes much more sense now.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre