linux-kernel - Re: [PATCH v3 2/5] media: hantro: Reduce H264 extra space for motion vectors

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Date:   Wed, 20 Nov 2019 21:44:09 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     Jonas Karlman <jonas@...boo.se>
Cc:     Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Hans Verkuil <hverkuil@...all.nl>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/5] media: hantro: Reduce H264 extra space for motion vectors

Hi Jonas,

On Thu, Nov 7, 2019 at 7:34 AM Jonas Karlman <jonas@...boo.se> wrote:
>
> A decoded 8-bit 4:2:0 frame need memory for up to 448 bytes per
> macroblock with additional 32 bytes on multi-core variants.
>
> Memory layout is as follow:
>
> +---------------------------+
> | Y-plane   256 bytes x MBs |
> +---------------------------+
> | UV-plane  128 bytes x MBs |
> +---------------------------+
> | MV buffer  64 bytes x MBs |
> +---------------------------+
> | MC sync          32 bytes |
> +---------------------------+
>
> Reduce the extra space allocated now that motion vector buffer offset no
> longer is based on the extra space.
>
> Only allocate extra space for 64 bytes x MBs of motion vector buffer
> and 32 bytes for multi-core sync.
>
> Fixes: a9471e25629b ("media: hantro: Add core bits to support H264 decoding")
> Signed-off-by: Jonas Karlman <jonas@...boo.se>
> Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
> ---
> Changes in v3:
>   - add memory layout to code comment (Boris)
> Changes in v2:
>   - updated commit message
> ---
>  drivers/staging/media/hantro/hantro_v4l2.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
>

Thanks for the patch!

What platform did you test it on and how? Was it tested with IOMMU enabled?

Best regards,
Tomasz

> diff --git a/drivers/staging/media/hantro/hantro_v4l2.c b/drivers/staging/media/hantro/hantro_v4l2.c
> index 3dae52abb96c..c8c896a06f58 100644
> --- a/drivers/staging/media/hantro/hantro_v4l2.c
> +++ b/drivers/staging/media/hantro/hantro_v4l2.c
> @@ -240,14 +240,30 @@ static int vidioc_try_fmt(struct file *file, void *priv, struct v4l2_format *f,
>                 v4l2_fill_pixfmt_mp(pix_mp, fmt->fourcc, pix_mp->width,
>                                     pix_mp->height);
>                 /*
> +                * A decoded 8-bit 4:2:0 NV12 frame may need memory for up to
> +                * 448 bytes per macroblock with additional 32 bytes on
> +                * multi-core variants.
> +                *
>                  * The H264 decoder needs extra space on the output buffers
>                  * to store motion vectors. This is needed for reference
>                  * frames.
> +                *
> +                * Memory layout is as follow:
> +                *
> +                * +---------------------------+
> +                * | Y-plane   256 bytes x MBs |
> +                * +---------------------------+
> +                * | UV-plane  128 bytes x MBs |
> +                * +---------------------------+
> +                * | MV buffer  64 bytes x MBs |
> +                * +---------------------------+
> +                * | MC sync          32 bytes |
> +                * +---------------------------+
>                  */
>                 if (ctx->vpu_src_fmt->fourcc == V4L2_PIX_FMT_H264_SLICE)
>                         pix_mp->plane_fmt[0].sizeimage +=
> -                               128 * DIV_ROUND_UP(pix_mp->width, 16) *
> -                                     DIV_ROUND_UP(pix_mp->height, 16);
> +                               64 * MB_WIDTH(pix_mp->width) *
> +                                    MB_WIDTH(pix_mp->height) + 32;
>         } else if (!pix_mp->plane_fmt[0].sizeimage) {
>                 /*
>                  * For coded formats the application can specify
> --
> 2.17.1
>