Le jeudi 27 octobre 2022 à 10:02 +0200, Andrzej Pietrasiewicz a écrit :
> The addresses of two elements of the segmap[][] member are passed to the
> hardware which expects 128-bit aligned addresses. However, without this
> patch offsetof(struct rkvdec_vp9_priv_tbl, segmap[0]) is an odd number
> (2421) but the hardware just ignores the 5 least significant bits of the
> address. As a result, the hardware writes the segmentation map to incorrect
> locations.
>
> Inserting 11 bytes of padding corrects this situation by making the said
> addresses divisible by 16 (i.e. aligned on a 128-bit boundary).
>
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
For backport purposes, perhaps add ?
Fixes: f25709c4ff15 ("media: rkvdec: Add the VP9 backend")
> ---
> drivers/staging/media/rkvdec/rkvdec-vp9.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/staging/media/rkvdec/rkvdec-vp9.c b/drivers/staging/media/rkvdec/rkvdec-vp9.c
> index d8c1c0db15c7..cfae99b40ccb 100644
> --- a/drivers/staging/media/rkvdec/rkvdec-vp9.c
> +++ b/drivers/staging/media/rkvdec/rkvdec-vp9.c
> @@ -84,6 +84,8 @@ struct rkvdec_vp9_probs {
> struct rkvdec_vp9_inter_frame_probs inter;
> struct rkvdec_vp9_intra_only_frame_probs intra_only;
> };
> + /* 128 bit alignment */
> + u8 padding1[11];
> };
>
> /* Data structure describing auxiliary buffer format. */
> @@ -1006,6 +1008,7 @@ static int rkvdec_vp9_start(struct rkvdec_ctx *ctx)
>
> ctx->priv = vp9_ctx;
>
> + BUILD_BUG_ON(sizeof(priv_tbl->probs) % 16); /* ensure probs size is 128-bit aligned */
> priv_tbl = dma_alloc_coherent(rkvdec->dev, sizeof(*priv_tbl),
> &vp9_ctx->priv_tbl.dma, GFP_KERNEL);
> if (!priv_tbl) {
