On Mon, Jan 09, 2017 at 11:19:32AM +0000, Chris Wilson wrote:
> On a non-llc system, the objects are created with .cache_level =
> CACHE_NONE and so the transition to uncached for scanout is a no-op.
> However, if the object was never written to, it will still be in the CPU
> domain (having been zeroed out by shmemfs). Those cachelines need to be
> flushed prior to display.
>
> Reported-by: Vito Caputo
> Fixes: a6a7cc4b7db6 ("drm/i915: Always flush the dirty CPU cache when pinning the scanout")
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: <drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx> # v4.10-rc1+
> ---
> drivers/gpu/drm/i915/i915_gem.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 76689b59fc90..bdb113ef8cfe 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3514,7 +3514,7 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
> vma->display_alignment = max_t(u64, vma->display_alignment, alignment);
>
> /* Treat this as an end-of-frame, like intel_user_framebuffer_dirty() */
> - if (obj->cache_dirty) {
> + if (obj->cache_dirty || obj->base.write_domain == I915_GEM_DOMAIN_CPU) {
Alternatively, should we set cache_dirty when initially allocating an
object? Ofc only if cpu_cache_is_coherent, like we do in other places.
Anyway, up to you which one you like more I'd say, this one looks correct
too.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> i915_gem_clflush_object(obj, true);
> intel_fb_obj_flush(obj, false, ORIGIN_DIRTYFB);
> }
> --
> 2.11.0
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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