Hi Tiffany, (Robin and Hans cc'd.) On Mon, Sep 21, 2015 at 08:26:11PM +0800, Tiffany Lin wrote: > 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); > } > > /*********************************************/ Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> Could you post a similar patch for videobuf2-dma-sg as well, please? This should probably go to stable (since when?). videobuf-dma-sg appears to be broken, too, but the fix is more changes than one or two lines. -- Kind regards, Sakari Ailus e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx -- 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
