From: Chris Wilson chris@chris-wilson.co.uk

commit be33805c65297611971003d72e7f9235e23ec84d upstream.

Forcing mocs:1 [used for our winsys follows-pte mode] to be cached caused display glitches. Though it is documented as deprecated (and so likely behaves as uncached) use the follow-pte bit and force it out of L3 cache.

Testcase: igt/kms_frontbuffer_tracking Testcase: igt/kms_big_fb Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Ayaz A Siddiqui ayaz.siddiqui@intel.com Cc: Lucas De Marchi lucas.demarchi@intel.com Cc: Matt Roper matthew.d.roper@intel.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20201015122138.30161-4-chris@c... (cherry picked from commit a04ac827366594c7244f60e9be79fcb404af69f0) Fixes: 849c0fe9e831 ("drm/i915/gt: Initialize reserved and unspecified MOCS indices") Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com [Rodrigo: Updated Fixes tag] Cc: stable@vger.kernel.org # 5.9.x --- drivers/gpu/drm/i915/gt/intel_mocs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_mocs.c b/drivers/gpu/drm/i915/gt/intel_mocs.c index b8f56e62158e..313e51e7d4f7 100644 --- a/drivers/gpu/drm/i915/gt/intel_mocs.c +++ b/drivers/gpu/drm/i915/gt/intel_mocs.c @@ -243,8 +243,9 @@ static const struct drm_i915_mocs_entry tgl_mocs_table[] = { * only, __init_mocs_table() take care to program unused index with * this entry. */ - MOCS_ENTRY(1, LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), - L3_3_WB), + MOCS_ENTRY(I915_MOCS_PTE, + LE_0_PAGETABLE | LE_TC_0_PAGETABLE, + L3_1_UC), GEN11_MOCS_ENTRIES,

/* Implicitly enable L1 - HDC:L1 + L3 + LLC */