[PATCH] media: mediatek: vcodec: Handle VP9 superframe bitstream with 8 sub-frames

[Nicolas Dufresne]

Hi,

Le dimanche 18 février 2024 à 19:59 +0800, Irui Wang a écrit :
> The VP9 bitstream has 8 sub-frames into one superframe, the superframe
> index validate failed when reach 8, modify the index checking so that the
> last sub-frame can be decoded normally.

When I first saw this patch I was concerned, since we don't allow bundling super
frame into the stateless API, but now I realize that this is for the stateful
decoder. Perhaps you can help me and possibly other reviewers with simply
stating that this is for stateful decoders.

> 
> Signed-off-by: Irui Wang <irui.wang at mediatek.com>
> ---
>  .../media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_if.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_if.c b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_if.c
> index 55355fa70090..4a9ced7348ee 100644
> --- a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_if.c
> @@ -526,7 +526,7 @@ static void vp9_swap_frm_bufs(struct vdec_vp9_inst *inst)
>  	/* if this super frame and it is not last sub-frame, get next fb for
>  	 * sub-frame decode
>  	 */
> -	if (vsi->sf_frm_cnt > 0 && vsi->sf_frm_idx != vsi->sf_frm_cnt - 1)
> +	if (vsi->sf_frm_cnt > 0 && vsi->sf_frm_idx != vsi->sf_frm_cnt)
>  		vsi->sf_next_ref_fb_idx = vp9_get_sf_ref_fb(inst);
>  }
>  
> @@ -735,7 +735,7 @@ static void get_free_fb(struct vdec_vp9_inst *inst, struct vdec_fb **out_fb)
>  
>  static int validate_vsi_array_indexes(struct vdec_vp9_inst *inst,
>  		struct vdec_vp9_vsi *vsi) {
> -	if (vsi->sf_frm_idx >= VP9_MAX_FRM_BUF_NUM - 1) {
> +	if (vsi->sf_frm_idx >= VP9_MAX_FRM_BUF_NUM) {

nit: I'd propose to define a new maximum (contractions allowed):

  #define VP9_MAX_NUM_SUPER_FRAMES 8

This way you can revisit bunch of `VP9_MAX_FRM_BUF_NUM-1`, and make the overall
code a bit more human readable. There is no relation between VP9_MAX_FRM_BUF_NUM
and this maximum. The limits simply comes from the fact
frames_in_superframe_minus_1 is expressed with 3 bits.

regards,
Nicolas

p.s. your change looks good otherwise.

>  		mtk_vdec_err(inst->ctx, "Invalid vsi->sf_frm_idx=%u.", vsi->sf_frm_idx);
>  		return -EIO;
>  	}