vb2_dc_prepare use the number of SG entries dma_map_sg_attrs return. But in dma_sync_sg_for_device, it use lengths of each SG entries before dma_map_sg_attrs. dma_map_sg_attrs will concatenate SGs until dma length > dma seg bundary. sgt->nents will less than sgt->orig_nents. Using SG entries after dma_map_sg_attrs in vb2_dc_prepare will make some SGs are not sync to device. After add DMA_ATTR_SKIP_CPU_SYNC in vb2_dc_get_userptr to remove sync data to device twice. Device randomly get incorrect data because some SGs are not sync to device. Change to use number of SG entries before dma_map_sg_attrs in vb2_dc_prepare to prevent this issue. Signed-off-by: Tiffany Lin <tiffany.lin@xxxxxxxxxxxx> --- drivers/media/v4l2-core/videobuf2-dma-contig.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 2397ceb..c5d00bd 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c @@ -100,7 +100,7 @@ static void vb2_dc_prepare(void *buf_priv) if (!sgt || buf->db_attach) return; - dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); + dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); } static void vb2_dc_finish(void *buf_priv) @@ -112,7 +112,7 @@ static void vb2_dc_finish(void *buf_priv) if (!sgt || buf->db_attach) return; - dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir); + dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); } /*********************************************/ -- 1.8.1.1.dirty -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
