[PATCH 4/4] media: vivid: synchronize imported DMA-BUFs for CPU access

[Karl Mehltretter]

vivid accesses imported DMA-BUFs with the CPU without cache
synchronization, leaving physical RAM stale after capture.

Set uses_cpu_access to bracket the driver's CPU access.

On a Pi 400, stale frames fell from 25/96 to 0/96 with this change.

Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@xxxxxxxxx>
---
 drivers/media/test-drivers/vivid/vivid-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/test-drivers/vivid/vivid-core.c b/drivers/media/test-drivers/vivid/vivid-core.c
index 62cfb5feb2cf5..e3aa1fc3bcf75 100644
--- a/drivers/media/test-drivers/vivid/vivid-core.c
+++ b/drivers/media/test-drivers/vivid/vivid-core.c
@@ -925,6 +925,7 @@ static int vivid_create_queue(struct vivid_dev *dev,
 	q->ops = ops;
 	q->mem_ops = allocators[dev->inst] == 1 ? &vb2_dma_contig_memops :
 						  &vb2_vmalloc_memops;
+	q->uses_cpu_access = true;
 	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
 	q->min_reqbufs_allocation = min_reqbufs_allocation;
 	q->lock = &dev->mutex;
-- 
2.47.3