Date:   Sat, 12 Sep 2020 15:31:59 +0530
From:   Kaaira Gupta <kgupta@...iitr.ac.in>
To:     Kieran Bingham <kieran.bingham@...asonboard.com>
Cc:     Helen Koike <helen.koike@...labora.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/9] media: vimc: Add get_frame callback

On Thu, Aug 20, 2020 at 04:36:56PM +0100, Kieran Bingham wrote:
> Hi Kaaira,
> 
> On 19/08/2020 19:04, Kaaira Gupta wrote:
> > In the process of making vimc compatible for multiple streams, we need
> > to create a frame passing process such that two different entities can
> > get the frame from a common entity. This isn't possible currently without
> > calling process_frame twice for the common entity, as process_frames
> > returns the frame which gets passed on.
> > 
> > So, to take care of this, add a get_frame callback to vimc device and
> > use it to get the frames for an entity from previous entity instead of
> > returning and passing the frames as an argument in process_frame.
> > 
> > Signed-off-by: Kaaira Gupta <kgupta@...iitr.ac.in>
> > ---
> >  .../media/test-drivers/vimc/vimc-capture.c    | 18 +++++++++++++++---
> >  drivers/media/test-drivers/vimc/vimc-common.h |  7 ++++---
> >  .../media/test-drivers/vimc/vimc-debayer.c    | 19 ++++++++++++++++---
> >  drivers/media/test-drivers/vimc/vimc-scaler.c | 18 +++++++++++++++---
> >  drivers/media/test-drivers/vimc/vimc-sensor.c | 11 +++++++++--
> >  .../media/test-drivers/vimc/vimc-streamer.c   | 10 ++++++----
> >  6 files changed, 65 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/media/test-drivers/vimc/vimc-capture.c b/drivers/media/test-drivers/vimc/vimc-capture.c
> > index c63496b17b9a..a8cbb8e4d5ba 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-capture.c
> > +++ b/drivers/media/test-drivers/vimc/vimc-capture.c
> > @@ -355,12 +355,13 @@ static void vimc_cap_unregister(struct vimc_ent_device *ved)
> >  	video_unregister_device(&vcap->vdev);
> >  }
> >  
> > -static void *vimc_cap_process_frame(struct vimc_ent_device *ved,
> > -				    const void *frame)
> > +static int vimc_cap_process_frame(struct vimc_ent_device *ved)
> >  {
> >  	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
> >  						    ved);
> >  	struct vimc_cap_buffer *vimc_buf;
> > +	struct v4l2_subdev *sd;
> > +	const void *frame;
> >  	void *vbuf;
> >  
> >  	spin_lock(&vcap->qlock);
> > @@ -370,7 +371,7 @@ static void *vimc_cap_process_frame(struct vimc_ent_device *ved,
> >  					    typeof(*vimc_buf), list);
> >  	if (!vimc_buf) {
> >  		spin_unlock(&vcap->qlock);
> > -		return ERR_PTR(-EAGAIN);
> > +		return -EAGAIN;
> >  	}
> >  
> >  	/* Remove this entry from the list */
> > @@ -385,12 +386,22 @@ static void *vimc_cap_process_frame(struct vimc_ent_device *ved,
> >  
> >  	vbuf = vb2_plane_vaddr(&vimc_buf->vb2.vb2_buf, 0);
> >  
> > +	sd = media_entity_to_v4l2_subdev(vimc_get_source_entity(ved->ent));
> > +	ved = v4l2_get_subdevdata(sd);
> > +	frame = ved->get_frame(ved);
> 
> Hrm, this code block is used in several places throughout this patch,
> and it aliases the function parameter ved to a new device which isn't
> nice. Not a problem as long as it's not used for the original VED after
> of course.
> 
> But I wonder if we should instead add a helper into vimc-common.c:
> 
> struct vimc_ent_device *vimc_get_source_ved(struct vimc_ent_device *ved)
> {
> 	struct media_entity *ent;
> 	struct v4l2_subdev *sd;
> 
> 	ent = vimc_get_source_entity(ved->ent);
> 	if (!ent)
> 		return NULL;
> 
> 	sd = media_entity_to_v4l2_subdev(ent);
> 
> 	return v4l2_get_subdevdata(sd);
> }
> 
> It might not be necessary though, just an idea. If you like it, it can
> be a patch on it's own after the vimc_get_source_entity() moving patch.

Yes indeed the source ved is calculated at many places in the entire
driver (other than this patchset as well), so if you like I can add a
helper for that.

> 
> 
> But it does show that vimc_get_source_entity() can return NULL which
> might have to be checked... though perhaps we 'know' it will always be
> valid ...
> 
> Also, following the links for each entity, for each frame sounds like
> quite a lot of work. I wonder if the active source entity should be
> cached in each VED ...

is caching only for calculating the frame okay? If it is I can do it in
this series itself if you like

> 
> That could be done on top anyway...
> 
> Overall, this looks like it will work, so with comments addressed how
> you wish,
> 
> Reviewed-by: Kieran Bingham <kieran.bingham@...asonboard.com>
> 
> 
> > +
> >  	memcpy(vbuf, frame, vcap->format.sizeimage);
> >  
> >  	/* Set it as ready */
> >  	vb2_set_plane_payload(&vimc_buf->vb2.vb2_buf, 0,
> >  			      vcap->format.sizeimage);
> >  	vb2_buffer_done(&vimc_buf->vb2.vb2_buf, VB2_BUF_STATE_DONE);
> > +
> > +	return 0;
> > +}
> > +
> > +static void *vimc_cap_get_frame(struct vimc_ent_device *ved)
> > +{
> >  	return NULL;
> >  }
> >  
> > @@ -455,6 +466,7 @@ static struct vimc_ent_device *vimc_cap_add(struct vimc_device *vimc,
> >  	vcap->ved.ent = &vcap->vdev.entity;
> >  	vcap->ved.process_frame = vimc_cap_process_frame;
> >  	vcap->ved.vdev_get_format = vimc_cap_get_format;
> > +	vcap->ved.get_frame = vimc_cap_get_frame;
> >  	vcap->ved.dev = vimc->mdev.dev;
> >  
> >  	/* Initialize the video_device struct */
> > diff --git a/drivers/media/test-drivers/vimc/vimc-common.h b/drivers/media/test-drivers/vimc/vimc-common.h
> > index 4c580d854007..287d66edff49 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-common.h
> > +++ b/drivers/media/test-drivers/vimc/vimc-common.h
> > @@ -85,7 +85,8 @@ struct vimc_pix_map {
> >   *
> >   * @dev:		a pointer of the device struct of the driver
> >   * @ent:		the pointer to struct media_entity for the node
> > - * @process_frame:	callback send a frame to that node
> > + * @get_frame:		callback that sends a frame processed by the entity
> 
> s/sends a/obtains the/
> 
> 
> 
> > + * @process_frame:	callback that processes a frame
> >   * @vdev_get_format:	callback that returns the current format a pad, used
> >   *			only when is_media_entity_v4l2_video_device(ent) returns
> >   *			true
> > @@ -101,8 +102,8 @@ struct vimc_pix_map {
> >  struct vimc_ent_device {
> >  	struct device *dev;
> >  	struct media_entity *ent;
> > -	void * (*process_frame)(struct vimc_ent_device *ved,
> > -				const void *frame);
> > +	void * (*get_frame)(struct vimc_ent_device *ved);
> > +	int (*process_frame)(struct vimc_ent_device *ved);
> >  	void (*vdev_get_format)(struct vimc_ent_device *ved,
> >  			      struct v4l2_pix_format *fmt);
> >  };
> > diff --git a/drivers/media/test-drivers/vimc/vimc-debayer.c b/drivers/media/test-drivers/vimc/vimc-debayer.c
> > index c3f6fef34f68..f61e6e8899ac 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-debayer.c
> > +++ b/drivers/media/test-drivers/vimc/vimc-debayer.c
> > @@ -491,17 +491,22 @@ static void vimc_deb_calc_rgb_sink(struct vimc_deb_device *vdeb,
> >  	}
> >  }
> >  
> > -static void *vimc_deb_process_frame(struct vimc_ent_device *ved,
> > -				    const void *sink_frame)
> > +static int vimc_deb_process_frame(struct vimc_ent_device *ved)
> >  {
> >  	struct vimc_deb_device *vdeb = container_of(ved, struct vimc_deb_device,
> >  						    ved);
> >  	unsigned int rgb[3];
> >  	unsigned int i, j;
> > +	struct v4l2_subdev *sd;
> > +	const void *sink_frame;
> >  
> >  	/* If the stream in this node is not active, just return */
> >  	if (!vdeb->src_frame)
> > -		return ERR_PTR(-EINVAL);
> > +		return -EINVAL;
> > +
> > +	sd = media_entity_to_v4l2_subdev(vimc_get_source_entity(ved->ent));
> > +	ved = v4l2_get_subdevdata(sd);
> > +	sink_frame = ved->get_frame(ved);
> >  
> >  	for (i = 0; i < vdeb->sink_fmt.height; i++)
> >  		for (j = 0; j < vdeb->sink_fmt.width; j++) {
> > @@ -509,6 +514,13 @@ static void *vimc_deb_process_frame(struct vimc_ent_device *ved,
> >  			vdeb->set_rgb_src(vdeb, i, j, rgb);
> >  		}
> >  
> > +	return 0;
> > +}
> > +
> > +static void *vimc_deb_get_frame(struct vimc_ent_device *ved)
> > +{
> > +	struct vimc_deb_device *vdeb = container_of(ved, struct vimc_deb_device,
> > +						    ved);
> >  	return vdeb->src_frame;
> >  }
> >  
> > @@ -593,6 +605,7 @@ static struct vimc_ent_device *vimc_deb_add(struct vimc_device *vimc,
> >  		goto err_free_hdl;
> >  
> >  	vdeb->ved.process_frame = vimc_deb_process_frame;
> > +	vdeb->ved.get_frame = vimc_deb_get_frame;
> >  	vdeb->ved.dev = vimc->mdev.dev;
> >  	vdeb->mean_win_size = vimc_deb_ctrl_mean_win_size.def;
> >  
> > diff --git a/drivers/media/test-drivers/vimc/vimc-scaler.c b/drivers/media/test-drivers/vimc/vimc-scaler.c
> > index 121fa7d62a2e..347f9cd4a168 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-scaler.c
> > +++ b/drivers/media/test-drivers/vimc/vimc-scaler.c
> > @@ -455,18 +455,29 @@ static void vimc_sca_fill_src_frame(const struct vimc_sca_device *const vsca,
> >  			vimc_sca_scale_pix(vsca, i, j, sink_frame);
> >  }
> >  
> > -static void *vimc_sca_process_frame(struct vimc_ent_device *ved,
> > -				    const void *sink_frame)
> > +static int vimc_sca_process_frame(struct vimc_ent_device *ved)
> >  {
> >  	struct vimc_sca_device *vsca = container_of(ved, struct vimc_sca_device,
> >  						    ved);
> > +	const void *sink_frame;
> > +	struct v4l2_subdev *sd;
> >  
> >  	/* If the stream in this node is not active, just return */
> >  	if (!vsca->src_frame)
> > -		return ERR_PTR(-EINVAL);
> > +		return -EINVAL;
> >  
> > +	sd = media_entity_to_v4l2_subdev(vimc_get_source_entity(ved->ent));
> > +	ved = v4l2_get_subdevdata(sd);
> > +	sink_frame = ved->get_frame(ved);
> >  	vimc_sca_fill_src_frame(vsca, sink_frame);
> >  
> > +	return 0;
> > +};
> > +
> > +static void *vimc_sca_get_frame(struct vimc_ent_device *ved)
> > +{
> > +	struct vimc_sca_device *vsca = container_of(ved, struct vimc_sca_device,
> > +						    ved);
> >  	return vsca->src_frame;
> >  };
> >  
> > @@ -505,6 +516,7 @@ static struct vimc_ent_device *vimc_sca_add(struct vimc_device *vimc,
> >  	}
> >  
> >  	vsca->ved.process_frame = vimc_sca_process_frame;
> > +	vsca->ved.get_frame = vimc_sca_get_frame;
> >  	vsca->ved.dev = vimc->mdev.dev;
> >  
> >  	/* Initialize the frame format */
> > diff --git a/drivers/media/test-drivers/vimc/vimc-sensor.c b/drivers/media/test-drivers/vimc/vimc-sensor.c
> > index ba5db5a150b4..32a2c39de2cd 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-sensor.c
> > +++ b/drivers/media/test-drivers/vimc/vimc-sensor.c
> > @@ -190,8 +190,7 @@ static const struct v4l2_subdev_pad_ops vimc_sen_pad_ops = {
> >  	.set_fmt		= vimc_sen_set_fmt,
> >  };
> >  
> > -static void *vimc_sen_process_frame(struct vimc_ent_device *ved,
> > -				    const void *sink_frame)
> > +static int vimc_sen_process_frame(struct vimc_ent_device *ved)
> >  {
> >  	struct vimc_sen_device *vsen = container_of(ved, struct vimc_sen_device,
> >  						    ved);
> > @@ -238,6 +237,13 @@ static void *vimc_sen_process_frame(struct vimc_ent_device *ved,
> >  		break;
> >  	}
> >  
> > +	return 0;
> > +}
> > +
> > +static void *vimc_sen_get_frame(struct vimc_ent_device *ved)
> > +{
> > +	struct vimc_sen_device *vsen = container_of(ved, struct vimc_sen_device,
> > +						    ved);
> >  	return vsen->frame;
> >  }
> >  
> > @@ -429,6 +435,7 @@ static struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
> >  		goto err_free_tpg;
> >  
> >  	vsen->ved.process_frame = vimc_sen_process_frame;
> > +	vsen->ved.get_frame = vimc_sen_get_frame;
> >  	vsen->ved.dev = vimc->mdev.dev;
> >  
> >  	/* Initialize the frame format */
> > diff --git a/drivers/media/test-drivers/vimc/vimc-streamer.c b/drivers/media/test-drivers/vimc/vimc-streamer.c
> > index 4f8384246042..c1644d69686d 100644
> > --- a/drivers/media/test-drivers/vimc/vimc-streamer.c
> > +++ b/drivers/media/test-drivers/vimc/vimc-streamer.c
> > @@ -125,7 +125,8 @@ static int vimc_streamer_pipeline_init(struct vimc_stream *stream,
> >  static int vimc_streamer_thread(void *data)
> >  {
> >  	struct vimc_stream *stream = data;
> > -	u8 *frame = NULL;
> > +	struct vimc_ent_device *ved;
> > +	int ret;
> >  	int i;
> >  
> >  	set_freezable();
> > @@ -136,9 +137,10 @@ static int vimc_streamer_thread(void *data)
> >  			break;
> >  
> >  		for (i = stream->pipe_size - 1; i >= 0; i--) {
> > -			frame = stream->ved_pipeline[i]->process_frame(
> > -					stream->ved_pipeline[i], frame);
> > -			if (!frame || IS_ERR(frame))
> > +			ved = stream->ved_pipeline[i];
> > +			ret = ved->process_frame(ved);
> > +
> > +			if (ret)
> >  				break;
> >  		}
> >  		//wait for 60hz
> > 
> 
> -- 
> Regards
> --
> Kieran

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