[PATCH] drm/xe: Add mmio read before GGTT invalidate

[Lucas De Marchi]

On Wed, Oct 23, 2024 at 03:12:00PM -0700, Matthew Brost wrote:
>On LNL without a mmio read before a GGTT invalidate the GuC can
>incorrectly read the GGTT scratch page upon next access leading to jobs
>not getting scheduled. A mmio read before a GGTT invalidate seems to fix
>this. Since a GGTT invalidate is not a hot code path, blindly do a mmio
>read before each GGTT invalidate.
>
>Cc: John Harrison <John.C.Harrison at Intel.com>
>Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>Cc: stable at vger.kernel.org
>Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
>Reported-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
>Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3164
>Signed-off-by: Matthew Brost <matthew.brost at intel.com>

Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>

and applied, thanks.

Lucas De Marchi