[1/5] drm/i915/gem: Flush the pwrite through the chipset before signaling
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Message ID 20191206105527.1130413-1-chris@chris-wilson.co.uk
State New
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Series
  • [1/5] drm/i915/gem: Flush the pwrite through the chipset before signaling
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Commit Message

Chris Wilson Dec. 6, 2019, 10:55 a.m. UTC
Before we signal the fence to indicate completion, ensure the pwrite
through the indirect GGTT is coherent (as best as we know) in memory.
Any listeners to the fence may start immediately and sample from the
backing store prior to the writes being posted, thus seeing stale data.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Tvrtko Ursulin Dec. 6, 2019, 11:34 a.m. UTC | #1
On 06/12/2019 10:55, Chris Wilson wrote:
> Before we signal the fence to indicate completion, ensure the pwrite
> through the indirect GGTT is coherent (as best as we know) in memory.
> Any listeners to the fence may start immediately and sample from the
> backing store prior to the writes being posted, thus seeing stale data.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_gem.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 98b65b718e1a..919d3a723c50 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -670,11 +670,12 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
>   		user_data += page_length;
>   		offset += page_length;
>   	}
> +
> +	intel_gt_flush_ggtt_writes(ggtt->vm.gt);
>   	intel_frontbuffer_flush(obj->frontbuffer, ORIGIN_CPU);
>   
>   	i915_gem_object_unlock_fence(obj, fence);
>   out_unpin:
> -	intel_gt_flush_ggtt_writes(ggtt->vm.gt);
>   	if (drm_mm_node_allocated(&node)) {
>   		ggtt->vm.clear_range(&ggtt->vm, node.start, node.size);
>   		remove_mappable_node(ggtt, &node);
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko

Patch
diff mbox series

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 98b65b718e1a..919d3a723c50 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -670,11 +670,12 @@  i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
 		user_data += page_length;
 		offset += page_length;
 	}
+
+	intel_gt_flush_ggtt_writes(ggtt->vm.gt);
 	intel_frontbuffer_flush(obj->frontbuffer, ORIGIN_CPU);
 
 	i915_gem_object_unlock_fence(obj, fence);
 out_unpin:
-	intel_gt_flush_ggtt_writes(ggtt->vm.gt);
 	if (drm_mm_node_allocated(&node)) {
 		ggtt->vm.clear_range(&ggtt->vm, node.start, node.size);
 		remove_mappable_node(ggtt, &node);