From: John Harrison John.C.Harrison@Intel.com
Direction from hardware is that ring buffers should never be mapped via the BAR on systems with LLC. There are too many caching pitfalls due to the way BAR accesses are routed. So it is safest to just not use it.
Signed-off-by: John Harrison John.C.Harrison@Intel.com Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound anywhere") Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com Cc: intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org # v4.9+ Tested-by: Jouni Högander jouni.hogander@intel.com Reviewed-by: Daniele Ceraolo Spurio daniele.ceraolospurio@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-3-John.... (cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919) Signed-off-by: Jani Nikula jani.nikula@intel.com (cherry picked from commit 85636167e3206c3fbd52254fc432991cc4e90194) Signed-off-by: John Harrison John.C.Harrison@Intel.com --- drivers/gpu/drm/i915/intel_ringbuffer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 3b8218dd9bb1..979d130b24c4 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -1083,7 +1083,7 @@ int intel_ring_pin(struct intel_ring *ring, if (unlikely(ret)) return ret;
- if (i915_vma_is_map_and_fenceable(vma)) + if (i915_vma_is_map_and_fenceable(vma) && !HAS_LLC(vma->vm->i915)) addr = (void __force *)i915_vma_pin_iomap(vma); else addr = i915_gem_object_pin_map(vma->obj, map); @@ -1118,7 +1118,7 @@ void intel_ring_unpin(struct intel_ring *ring) /* Discard any unused bytes beyond that submitted to hw. */ intel_ring_reset(ring, ring->tail);
- if (i915_vma_is_map_and_fenceable(ring->vma)) + if (i915_vma_is_map_and_fenceable(ring->vma) && !HAS_LLC(ring->vma->vm->i915)) i915_vma_unpin_iomap(ring->vma); else i915_gem_object_unpin_map(ring->vma->obj);