Re: [v3] media: mediatek: vcodec: fix AV1 decoding on MT8188

[Eugen Hristev <eugen.hristev@collabora.com>]

Hi Xiaoyong,

On 8/3/23 14:10, Xiaoyong Lu wrote:
> Fix AV1 decoding failure when the iova is 36bit.
> 
> Before this fix, the decoder was accessing incorrect addresses with 36bit
> iova tile buffer, leading to iommu faults.
> 
> Fixes: 2f5d0aef37c6 ("media: mediatek: vcodec: support stateless AV1 decoder")
> Signed-off-by: Xiaoyong Lu<xiaoyong.lu@mediatek.com>
> ---
> Changes from v2:
> 
> - refine commit subject and message
> 
> Changes from v1:
> 
> - prefer '|' rather than '+'
> - prefer '&' rather than shift operation
> - add comments for address operations
> 
> v1:
> - VDEC HW can access tile buffer and decode normally.
> - Test ok by mt8195 32bit and mt8188 36bit iova.
> 
> ---
>   .../mediatek/vcodec/vdec/vdec_av1_req_lat_if.c       | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_av1_req_lat_if.c b/drivers/media/platform/mediatek/vcodec/vdec/vdec_av1_req_lat_if.c
> index 404a1a23fd402..e9f2393f6a883 100644
> --- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_av1_req_lat_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_av1_req_lat_if.c
> @@ -1658,9 +1658,9 @@ static void vdec_av1_slice_setup_tile_buffer(struct vdec_av1_slice_instance *ins
>   	u32 allow_update_cdf = 0;
>   	u32 sb_boundary_x_m1 = 0, sb_boundary_y_m1 = 0;
>   	int tile_info_base;
> -	u32 tile_buf_pa;
> +	u64 tile_buf_pa;
>   	u32 *tile_info_buf = instance->tile.va;
> -	u32 pa = (u32)bs->dma_addr;
> +	u64 pa = (u64)bs->dma_addr;

If it this is a dma address, can't we use dma_addr_t ? isn't it more 
generic? Or maybe you have a specific reason not to ?

>   
>   	if (uh->disable_cdf_update == 0)
>   		allow_update_cdf = 1;
> @@ -1673,8 +1673,12 @@ static void vdec_av1_slice_setup_tile_buffer(struct vdec_av1_slice_instance *ins
>   		tile_info_buf[tile_info_base + 0] = (tile_group->tile_size[tile_num] << 3);
>   		tile_buf_pa = pa + tile_group->tile_start_offset[tile_num];
>   
> -		tile_info_buf[tile_info_base + 1] = (tile_buf_pa >> 4) << 4;
> -		tile_info_buf[tile_info_base + 2] = (tile_buf_pa % 16) << 3;
> +		/* save av1 tile high 4bits(bit 32-35) address in lower 4 bits position
> +		 * and clear original for hw requirement.
> +		 */
> +		tile_info_buf[tile_info_base + 1] = (tile_buf_pa & 0xFFFFFFF0ull) |
> +			((tile_buf_pa & 0xF00000000ull) >> 32);
> +		tile_info_buf[tile_info_base + 2] = (tile_buf_pa & 0xFull) << 3;

Would it be better to use GENMASK if you plan to mask out some of the 
bits in the tile_buf_pa ?


>   
>   		sb_boundary_x_m1 =
>   			(tile->mi_col_starts[tile_col + 1] - tile->mi_col_starts[tile_col] - 1) &

Greetings,
Eugen