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SubjectRe: [PATCH 8/9] media: cedrus: Add start and stop decoder operations
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Hi,

On Wed, 2018-06-13 at 16:07 +0200, Maxime Ripard wrote:
> Some codec needs to perform some additional task when a decoding is started
> and stopped, and not only at every frame.
>
> For example, the H264 decoding support needs to allocate buffers that will
> be used in the decoding process, but do not need to change over time, or at
> each frame.
>
> In order to allow that for codecs, introduce a start and stop hook that
> will be called if present at start_streaming and stop_streaming time.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> ---
> .../platform/sunxi/cedrus/sunxi_cedrus_common.h | 2 ++
> .../platform/sunxi/cedrus/sunxi_cedrus_video.c | 14 +++++++++++++-
> 2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h
> index a2a507eb9fc9..20c78ec1f037 100644
> --- a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h
> +++ b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h
> @@ -120,6 +120,8 @@ struct sunxi_cedrus_dec_ops {
> enum sunxi_cedrus_irq_status (*irq_status)(struct sunxi_cedrus_ctx *ctx);
> void (*setup)(struct sunxi_cedrus_ctx *ctx,
> struct sunxi_cedrus_run *run);
> + int (*start)(struct sunxi_cedrus_ctx *ctx);
> + void (*stop)(struct sunxi_cedrus_ctx *ctx);
> void (*trigger)(struct sunxi_cedrus_ctx *ctx);
> };
>
> diff --git a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_video.c b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_video.c
> index fb7b081a5bb7..d93461178857 100644
> --- a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_video.c
> +++ b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_video.c
> @@ -416,6 +416,8 @@ static int sunxi_cedrus_buf_prepare(struct vb2_buffer *vb)
> static int sunxi_cedrus_start_streaming(struct vb2_queue *q, unsigned int count)
> {
> struct sunxi_cedrus_ctx *ctx = vb2_get_drv_priv(q);
> + struct sunxi_cedrus_dev *dev = ctx->dev;
> + int ret = 0;
>
> switch (ctx->vpu_src_fmt->fourcc) {
> case V4L2_PIX_FMT_MPEG2_FRAME:
> @@ -425,16 +427,26 @@ static int sunxi_cedrus_start_streaming(struct vb2_queue *q, unsigned int count)
> return -EINVAL;
> }
>
> - return 0;
> + if (V4L2_TYPE_IS_OUTPUT(q->type) &&

I suppose this check was put in place to ensure that ->start is only
called once, but what if start_streaming is called multiple times on
output? Am I totally unsure about whether the API guarantees that we
only get one start_streaming call per buffer queue, regardless of how
many userspace issues.

If we don't have such a guarantee, we probably need an internal
mechanism to avoid having ->start called more than once.

> + dev->dec_ops[ctx->current_codec]->start)
> + ret = dev->dec_ops[ctx->current_codec]->start(ctx);
> +
> + return ret;
> }
>
> static void sunxi_cedrus_stop_streaming(struct vb2_queue *q)
> {
> struct sunxi_cedrus_ctx *ctx = vb2_get_drv_priv(q);
> + struct sunxi_cedrus_dev *dev = ctx->dev;
> struct vb2_v4l2_buffer *vbuf;
> unsigned long flags;
>
> flush_scheduled_work();
> +
> + if (V4L2_TYPE_IS_OUTPUT(q->type) &&

Ditto.

Cheers,

Paul

> + dev->dec_ops[ctx->current_codec]->stop)
> + dev->dec_ops[ctx->current_codec]->stop(ctx);
> +
> for (;;) {
> spin_lock_irqsave(&ctx->dev->irq_lock, flags);
>
--
Paul Kocialkowski, Bootlin (formerly Free Electrons)
Embedded Linux and kernel engineering
https://bootlin.com[unhandled content-type:application/pgp-signature]
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