From: Jonathan Cavitt Date: Thu, 2 Nov 2023 17:58:31 +0000 (-0700) Subject: drm/i915/gt: Temporarily disable CPU caching into DMA for MTL X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=34df0a031d8f3488fe72627b041a1f82437fa6ec;p=linux.git drm/i915/gt: Temporarily disable CPU caching into DMA for MTL FIXME: It is suspected that some Address Translation Service (ATS) issue on IOMMU is causing CAT errors to occur on some MTL workloads. Applying a write barrier to the ppgtt set entry functions appeared to have no effect, so we must temporarily use I915_MAP_WC in the map_pt_dma class of functions on MTL until a proper ATS solution is found. Signed-off-by: Jonathan Cavitt CC: Chris Wilson Reviewed-by: Radhakrishna Sripada Acked-by: Andi Shyti Signed-off-by: Andi Shyti Link: https://patchwork.freedesktop.org/patch/msgid/20231102175831.872763-1-jonathan.cavitt@intel.com --- diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c index 4fbed27ef0ecc..21719563a602a 100644 --- a/drivers/gpu/drm/i915/gt/intel_gtt.c +++ b/drivers/gpu/drm/i915/gt/intel_gtt.c @@ -95,6 +95,16 @@ int map_pt_dma(struct i915_address_space *vm, struct drm_i915_gem_object *obj) void *vaddr; type = intel_gt_coherent_map_type(vm->gt, obj, true); + /* + * FIXME: It is suspected that some Address Translation Service (ATS) + * issue on IOMMU is causing CAT errors to occur on some MTL workloads. + * Applying a write barrier to the ppgtt set entry functions appeared + * to have no effect, so we must temporarily use I915_MAP_WC here on + * MTL until a proper ATS solution is found. + */ + if (IS_METEORLAKE(vm->i915)) + type = I915_MAP_WC; + vaddr = i915_gem_object_pin_map_unlocked(obj, type); if (IS_ERR(vaddr)) return PTR_ERR(vaddr); @@ -109,6 +119,16 @@ int map_pt_dma_locked(struct i915_address_space *vm, struct drm_i915_gem_object void *vaddr; type = intel_gt_coherent_map_type(vm->gt, obj, true); + /* + * FIXME: It is suspected that some Address Translation Service (ATS) + * issue on IOMMU is causing CAT errors to occur on some MTL workloads. + * Applying a write barrier to the ppgtt set entry functions appeared + * to have no effect, so we must temporarily use I915_MAP_WC here on + * MTL until a proper ATS solution is found. + */ + if (IS_METEORLAKE(vm->i915)) + type = I915_MAP_WC; + vaddr = i915_gem_object_pin_map(obj, type); if (IS_ERR(vaddr)) return PTR_ERR(vaddr);