Message-ID: <aa44957d-38e5-b799-2837-624a7cbbb3bb@xs4all.nl>
Date:   Wed, 9 Oct 2019 12:18:45 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Jernej Škrabec <jernej.skrabec@...l.net>
Cc:     mchehab@...nel.org, paul.kocialkowski@...tlin.com,
        mripard@...nel.org, pawel@...iak.com, m.szyprowski@...sung.com,
        kyungmin.park@...sung.com, tfiga@...omium.org, wens@...e.org,
        gregkh@...uxfoundation.org, boris.brezillon@...labora.com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devel@...verdev.osuosl.org, linux-arm-kernel@...ts.infradead.org,
        ezequiel@...labora.com, jonas@...boo.se
Subject: Re: [PATCH v2 0/6] media: cedrus: h264: Support multi-slice frames

On 10/7/19 9:01 PM, Jernej Škrabec wrote:
> Dne ponedeljek, 07. oktober 2019 ob 12:44:24 CEST je Hans Verkuil napisal(a):
>> Hi Jernej,
>>
>> On 9/29/19 10:00 PM, Jernej Skrabec wrote:
>>> This series adds support for decoding multi-slice H264 frames along with
>>> support for V4L2_DEC_CMD_FLUSH and V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF.
>>>
>>> Code was tested by modified ffmpeg, which can be found here:
>>> https://github.com/jernejsk/FFmpeg, branch mainline-test
>>> It has to be configured with at least following options:
>>> --enable-v4l2-request --enable-libudev --enable-libdrm
>>>
>>> Samples used for testing:
>>> http://jernej.libreelec.tv/videos/h264/BA1_FT_C.mp4
>>> http://jernej.libreelec.tv/videos/h264/h264.mp4
>>>
>>> Command line used for testing:
>>> ffmpeg -hwaccel drm -hwaccel_device /dev/dri/card0 -i h264.mp4 -pix_fmt
>>> bgra -f fbdev /dev/fb0
>>>
>>> Please note that V4L2_DEC_CMD_FLUSH was not tested because I'm
>>> not sure how. ffmpeg follows exactly which slice is last in frame
>>> and sets hold flag accordingly. Improper usage of hold flag would
>>> corrupt ffmpeg assumptions and it would probably crash. Any ideas
>>> how to test this are welcome!
>>>
>>> Thanks to Jonas for adjusting ffmpeg.
>>>
>>> Please let me know what you think.
>>>
>>> Best regards,
>>> Jernej
>>>
>>> Changes from v1:
>>> - added Rb tags
>>> - updated V4L2_DEC_CMD_FLUSH documentation
>>> - updated first slice detection in Cedrus
>>> - hold capture buffer flag is set according to source format
>>> - added v4l m2m stateless_(try_)decoder_cmd ioctl helpers
>>>
>>> Hans Verkuil (2):
>>>   vb2: add V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF
>>>   videodev2.h: add V4L2_DEC_CMD_FLUSH
>>>
>>> Jernej Skrabec (4):
>>>   media: v4l2-mem2mem: add stateless_(try_)decoder_cmd ioctl helpers
>>>   media: cedrus: Detect first slice of a frame
>>>   media: cedrus: h264: Support multiple slices per frame
>>>   media: cedrus: Add support for holding capture buffer
>>>  
>>>  Documentation/media/uapi/v4l/buffer.rst       | 13 ++++++
>>>  .../media/uapi/v4l/vidioc-decoder-cmd.rst     | 10 +++-
>>>  .../media/uapi/v4l/vidioc-reqbufs.rst         |  6 +++
>>>  .../media/videodev2.h.rst.exceptions          |  1 +
>>>  .../media/common/videobuf2/videobuf2-v4l2.c   |  8 +++-
>>>  drivers/media/v4l2-core/v4l2-mem2mem.c        | 35 ++++++++++++++
>>>  drivers/staging/media/sunxi/cedrus/cedrus.h   |  1 +
>>>  .../staging/media/sunxi/cedrus/cedrus_dec.c   | 11 +++++
>>>  .../staging/media/sunxi/cedrus/cedrus_h264.c  | 11 ++++-
>>>  .../staging/media/sunxi/cedrus/cedrus_hw.c    |  8 ++--
>>>  .../staging/media/sunxi/cedrus/cedrus_video.c | 14 ++++++
>>>  include/media/v4l2-mem2mem.h                  | 46 +++++++++++++++++++
>>>  include/media/videobuf2-core.h                |  3 ++
>>>  include/media/videobuf2-v4l2.h                |  5 ++
>>>  include/uapi/linux/videodev2.h                | 14 ++++--
>>>  15 files changed, 175 insertions(+), 11 deletions(-)
>>
>> I didn't want to make a v3 of this series, instead I hacked this patch that
>> will hopefully do all the locking right.
>>
>> Basically I moved all the 'held' related code into v4l2-mem2mem under
>> job_spinlock. This simplifies the driver code as well.
>>
>> But this is a hack that sits on top of this series. If your ffmpeg tests are
>> now successful, then I'll turn this into a proper series with correct
>> documentation (a lot of the comments are now wrong with this patch, so just
>> ignore that).
> 
> Thanks for looking into this! With small fix mentioned below, it works! Note 
> that both scenarios I tested (flushing during decoding and flushing after 
> decoding is finished) are focused on capture queue. In order to trigger output 
> queue flush, ffmpeg would need to queue multiple jobs and call flush before they 
> are all processed. This is not something I can do at this time. Maybe Jonas 
> can help with modifying ffmpeg appropriately. However, code for case seems 
> correct to me.
> 
>>
>> Regards,
>>
>> 	Hans
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c
>> b/drivers/media/v4l2-core/v4l2-mem2mem.c index 2677a07e4c9b..f81a8f2465ab
>> 100644
>> --- a/drivers/media/v4l2-core/v4l2-mem2mem.c
>> +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
>> @@ -412,25 +412,24 @@ static void v4l2_m2m_cancel_job(struct v4l2_m2m_ctx
>> *m2m_ctx) }
>>  }
>>
>> -void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
>> -			 struct v4l2_m2m_ctx *m2m_ctx)
>> +static bool _v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
>> +			  struct v4l2_m2m_ctx *m2m_ctx)
>>  {
>> -	unsigned long flags;
>> -
>> -	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
>>  	if (!m2m_dev->curr_ctx || m2m_dev->curr_ctx != m2m_ctx) {
>> -		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>>  		dprintk("Called by an instance not currently 
> running\n");
>> -		return;
>> +		return false;
>>  	}
>>
>>  	list_del(&m2m_dev->curr_ctx->queue);
>>  	m2m_dev->curr_ctx->job_flags &= ~(TRANS_QUEUED | TRANS_RUNNING);
>>  	wake_up(&m2m_dev->curr_ctx->finished);
>>  	m2m_dev->curr_ctx = NULL;
>> +	return true;
>> +}
>>
>> -	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> -
>> +static void v4l2_m2m_job_next(struct v4l2_m2m_dev *m2m_dev,
>> +		       struct v4l2_m2m_ctx *m2m_ctx)
>> +{
>>  	/* This instance might have more buffers ready, but since we do not
>>  	 * allow more than one job on the job_queue per instance, each has
>>  	 * to be scheduled separately after the previous one finishes. */
>> @@ -441,8 +440,113 @@ void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
>> */
>>  	schedule_work(&m2m_dev->job_work);
>>  }
>> +
>> +void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
>> +			 struct v4l2_m2m_ctx *m2m_ctx)
>> +{
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
>> +	if (!_v4l2_m2m_job_finish(m2m_dev, m2m_ctx)) {
>> +		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> +		return;
>> +	}
>> +	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> +
>> +	v4l2_m2m_job_next(m2m_dev, m2m_ctx);
>> +}
>>  EXPORT_SYMBOL(v4l2_m2m_job_finish);
>>
>> +void v4l2_m2m_job_finish_held(struct v4l2_m2m_dev *m2m_dev,
>> +			 struct v4l2_m2m_ctx *m2m_ctx,
>> +			 enum vb2_buffer_state state)
>> +{
>> +	struct vb2_v4l2_buffer *src_buf, *dst_buf;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
>> +	src_buf = v4l2_m2m_src_buf_remove(m2m_ctx);
>> +	dst_buf = v4l2_m2m_next_dst_buf(m2m_ctx);
>> +
>> +	if (!src_buf || !dst_buf) {
>> +		pr_err("Missing source and/or destination buffers\n");
>> +		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> +		return;
>> +	}
>> +	v4l2_m2m_buf_done(src_buf, state);
>> +	if (!dst_buf->is_held) {
>> +		v4l2_m2m_dst_buf_remove(m2m_ctx);
>> +		v4l2_m2m_buf_done(dst_buf, state);
>> +	}
>> +	if (!_v4l2_m2m_job_finish(m2m_dev, m2m_ctx)) {
>> +		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> +		return;
>> +	}
>> +	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> +
>> +	v4l2_m2m_job_next(m2m_dev, m2m_ctx);
>> +}
>> +EXPORT_SYMBOL(v4l2_m2m_job_finish_held);
>> +
>> +/**
>> + * v4l2_m2m_release_capture_buf() - check if the capture buffer should be
>> + * released
>> + *
>> + * @out_vb: the output buffer
>> + * @cap_vb: the capture buffer
>> + *
>> + * This helper function returns true if the current capture buffer should
>> + * be released to vb2. This is the case if the output buffer specified that
>> + * the capture buffer should be held (i.e. not returned to vb2) AND if the
>> + * timestamp of the capture buffer differs from the output buffer
>> timestamp. + *
>> + * This helper is to be called at the start of the device_run callback:
>> + *
>> + * .. code-block:: c
>> + *
>> + *	if (v4l2_m2m_release_capture_buf(out_vb, cap_vb)) {
>> + *		v4l2_m2m_dst_buf_remove(m2m_ctx);
>> + *		v4l2_m2m_buf_done(cap_vb, VB2_BUF_STATE_DONE);
>> + *		cap_vb = v4l2_m2m_next_dst_buf(m2m_ctx);
>> + *	}
>> + *	cap_vb->is_held = out_vb->flags & 
> V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
>> + *
>> + *	...
>> + *
>> + *	v4l2_m2m_buf_done(out_vb, VB2_BUF_STATE_DONE);
>> + *	if (!cap_vb->is_held) {
>> + *		v4l2_m2m_dst_buf_remove(m2m_ctx);
>> + *		v4l2_m2m_buf_done(cap_vb, VB2_BUF_STATE_DONE);
>> + *	}
>> + *
>> + * This allows for multiple output buffers to be used to fill in a single
>> + * capture buffer. This is typically used by stateless decoders where
>> + * multiple e.g. H.264 slices contribute to a single decoded frame.
>> + */
>> +struct vb2_v4l2_buffer *v4l2_m2m_release_capture_buf(struct v4l2_m2m_ctx
>> *m2m_ctx) +{
>> +	struct v4l2_m2m_dev *m2m_dev = m2m_ctx->m2m_dev;
>> +	struct vb2_v4l2_buffer *src, *dst;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
>> +	src = v4l2_m2m_next_src_buf(m2m_ctx);
>> +	dst = v4l2_m2m_next_dst_buf(m2m_ctx);
>> +
>> +	if (dst->is_held && dst->vb2_buf.copied_timestamp &&
>> +	    src->vb2_buf.timestamp != dst->vb2_buf.timestamp) {
>> +		dst->is_held = false;
>> +		v4l2_m2m_dst_buf_remove(m2m_ctx);
>> +		v4l2_m2m_buf_done(dst, VB2_BUF_STATE_DONE);
>> +		dst = v4l2_m2m_next_dst_buf(m2m_ctx);
>> +	}
>> +	dst->is_held = src->flags & V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
>> +	src->flags &= ~V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
>> +	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>> +	return dst;
>> +}
>> +EXPORT_SYMBOL(v4l2_m2m_release_capture_buf);
>> +
>>  int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
>>  		     struct v4l2_requestbuffers *reqbufs)
>>  {
>> @@ -1171,19 +1275,28 @@ int v4l2_m2m_ioctl_stateless_decoder_cmd(struct file
>> *file, void *priv, {
>>  	struct v4l2_fh *fh = file->private_data;
>>  	struct vb2_v4l2_buffer *out_vb, *cap_vb;
>> +	struct v4l2_m2m_dev *m2m_dev = fh->m2m_ctx->m2m_dev;
>> +	unsigned long flags;
>>  	int ret;
>>
>>  	ret = v4l2_m2m_ioctl_stateless_try_decoder_cmd(file, priv, dc);
>>  	if (ret < 0)
>>  		return ret;
>>
>> +	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
>>  	out_vb = v4l2_m2m_last_src_buf(fh->m2m_ctx);
>>  	cap_vb = v4l2_m2m_last_dst_buf(fh->m2m_ctx);
>>
>> -	if (out_vb)
>> +	if (out_vb && (out_vb->flags & V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF)) 
> {
>>  		out_vb->flags &= ~V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
>> -	else if (cap_vb && cap_vb->is_held)
>> -		v4l2_m2m_buf_done(cap_vb, VB2_BUF_STATE_DONE);
>> +	} else if (cap_vb && cap_vb->is_held) {
>> +		cap_vb->is_held = false;
>> +		if (m2m_dev->curr_ctx) {
> 
> Above condition should be negated.

Close. It should check that this buffer isn't currently being processed.
So:

		if (m2m_dev->curr_ctx != fh->m2m_ctx) {

Can you test with this change? If this works, then I'll post a proper
series for this.

Thanks!

	Hans

> 
> Best regards,
> Jernej
> 
>> +			v4l2_m2m_dst_buf_remove(fh->m2m_ctx);
>> +			v4l2_m2m_buf_done(cap_vb, 
> VB2_BUF_STATE_DONE);
>> +		}
>> +	}
>> +	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
>>
>>  	return 0;
>>  }
>> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
>> b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c index
>> 67f7d4326fc1..4e30f263b427 100644
>> --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
>> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
>> @@ -30,14 +30,7 @@ void cedrus_device_run(void *priv)
>>  	struct media_request *src_req;
>>
>>  	run.src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
>> -	run.dst = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
>> -
>> -	if (v4l2_m2m_release_capture_buf(run.src, run.dst)) {
>> -		v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
>> -		v4l2_m2m_buf_done(run.dst, VB2_BUF_STATE_DONE);
>> -		run.dst = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
>> -	}
>> -	run.dst->is_held = run.src->flags & 
> V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
>> +	run.dst = v4l2_m2m_release_capture_buf(ctx->fh.m2m_ctx);
>>
>>  	run.first_slice = !run.dst->vb2_buf.copied_timestamp ||
>>  		run.src->vb2_buf.timestamp != run.dst-
>> vb2_buf.timestamp;
>> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
>> b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c index
>> 99fedec80224..242cad82cc8c 100644
>> --- a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
>> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
>> @@ -103,7 +103,6 @@ static irqreturn_t cedrus_irq(int irq, void *data)
>>  {
>>  	struct cedrus_dev *dev = data;
>>  	struct cedrus_ctx *ctx;
>> -	struct vb2_v4l2_buffer *src_buf, *dst_buf;
>>  	enum vb2_buffer_state state;
>>  	enum cedrus_irq_status status;
>>
>> @@ -121,26 +120,12 @@ static irqreturn_t cedrus_irq(int irq, void *data)
>>  	dev->dec_ops[ctx->current_codec]->irq_disable(ctx);
>>  	dev->dec_ops[ctx->current_codec]->irq_clear(ctx);
>>
>> -	src_buf = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
>> -	dst_buf = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
>> -
>> -	if (!src_buf || !dst_buf) {
>> -		v4l2_err(&dev->v4l2_dev,
>> -			 "Missing source and/or destination 
> buffers\n");
>> -		return IRQ_HANDLED;
>> -	}
>> -
>>  	if (status == CEDRUS_IRQ_ERROR)
>>  		state = VB2_BUF_STATE_ERROR;
>>  	else
>>  		state = VB2_BUF_STATE_DONE;
>>
>> -	v4l2_m2m_buf_done(src_buf, state);
>> -	if (!dst_buf->is_held) {
>> -		v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
>> -		v4l2_m2m_buf_done(dst_buf, state);
>> -	}
>> -	v4l2_m2m_job_finish(ctx->dev->m2m_dev, ctx->fh.m2m_ctx);
>> +	v4l2_m2m_job_finish_held(ctx->dev->m2m_dev, ctx->fh.m2m_ctx, state);
>>
>>  	return IRQ_HANDLED;
>>  }
>> diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
>> index 8ae2f56c7fa3..48ca7d3eaa3d 100644
>> --- a/include/media/v4l2-mem2mem.h
>> +++ b/include/media/v4l2-mem2mem.h
>> @@ -173,6 +173,10 @@ void v4l2_m2m_try_schedule(struct v4l2_m2m_ctx
>> *m2m_ctx); void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
>>  			 struct v4l2_m2m_ctx *m2m_ctx);
>>
>> +void v4l2_m2m_job_finish_held(struct v4l2_m2m_dev *m2m_dev,
>> +			 struct v4l2_m2m_ctx *m2m_ctx,
>> +			 enum vb2_buffer_state state);
>> +
>>  static inline void
>>  v4l2_m2m_buf_done(struct vb2_v4l2_buffer *buf, enum vb2_buffer_state state)
>> {
>> @@ -644,47 +648,7 @@ void v4l2_m2m_buf_copy_metadata(const struct
>> vb2_v4l2_buffer *out_vb, struct vb2_v4l2_buffer *cap_vb,
>>  				bool copy_frame_flags);
>>
>> -/**
>> - * v4l2_m2m_release_capture_buf() - check if the capture buffer should be
>> - * released
>> - *
>> - * @out_vb: the output buffer
>> - * @cap_vb: the capture buffer
>> - *
>> - * This helper function returns true if the current capture buffer should
>> - * be released to vb2. This is the case if the output buffer specified that
>> - * the capture buffer should be held (i.e. not returned to vb2) AND if the
>> - * timestamp of the capture buffer differs from the output buffer
>> timestamp. - *
>> - * This helper is to be called at the start of the device_run callback:
>> - *
>> - * .. code-block:: c
>> - *
>> - *	if (v4l2_m2m_release_capture_buf(out_vb, cap_vb)) {
>> - *		v4l2_m2m_dst_buf_remove(m2m_ctx);
>> - *		v4l2_m2m_buf_done(cap_vb, VB2_BUF_STATE_DONE);
>> - *		cap_vb = v4l2_m2m_next_dst_buf(m2m_ctx);
>> - *	}
>> - *	cap_vb->is_held = out_vb->flags & 
> V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF;
>> - *
>> - *	...
>> - *
>> - *	v4l2_m2m_buf_done(out_vb, VB2_BUF_STATE_DONE);
>> - *	if (!cap_vb->is_held) {
>> - *		v4l2_m2m_dst_buf_remove(m2m_ctx);
>> - *		v4l2_m2m_buf_done(cap_vb, VB2_BUF_STATE_DONE);
>> - *	}
>> - *
>> - * This allows for multiple output buffers to be used to fill in a single
>> - * capture buffer. This is typically used by stateless decoders where
>> - * multiple e.g. H.264 slices contribute to a single decoded frame.
>> - */
>> -static inline bool v4l2_m2m_release_capture_buf(const struct
>> vb2_v4l2_buffer *out_vb, -					
> 	const struct vb2_v4l2_buffer *cap_vb)
>> -{
>> -	return cap_vb->is_held && cap_vb->vb2_buf.copied_timestamp &&
>> -	       out_vb->vb2_buf.timestamp != cap_vb->vb2_buf.timestamp;
>> -}
>> +struct vb2_v4l2_buffer *v4l2_m2m_release_capture_buf(struct v4l2_m2m_ctx
>> *m2m_ctx);
>>
>>  /* v4l2 request helper */
> 
> 
> 
> 

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