linux-media.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Kieran Bingham <kieran.bingham@ideasonboard.com>
To: Kaaira Gupta <kgupta@es.iitr.ac.in>,
	Helen Koike <helen.koike@collabora.com>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 7/9] media: vimc: Dynamically allocate stream struct
Date: Wed, 2 Sep 2020 11:29:31 +0100	[thread overview]
Message-ID: <7300d7ab-2be0-a6c6-b506-5af8b4a9b893@ideasonboard.com> (raw)
In-Reply-To: <20200819180442.11630-8-kgupta@es.iitr.ac.in>

Hi Kaaira,

On 19/08/2020 19:04, Kaaira Gupta wrote:
> Multiple streams will share same stream struct if we want them to run on
> same thread. So remove it from vimc_cap struct so that it doesn't get
> destroyed when one of the capture does, and allocate it memory
> dynamically. Use kref with it as it will be used by multiple captures.
> 

Is the vimc_stream stuct the context of the streamer? or of each 'stream'?

If it's the streamer - then can't we store this (non-dynamically) as
part of the Sensor node, to avoid kzalloc/freeing it ?


> Signed-off-by: Kaaira Gupta <kgupta@es.iitr.ac.in>
> ---
>  drivers/media/test-drivers/vimc/vimc-capture.c  | 15 +++++++++++----
>  drivers/media/test-drivers/vimc/vimc-streamer.c | 17 ++++++-----------
>  drivers/media/test-drivers/vimc/vimc-streamer.h |  2 ++
>  3 files changed, 19 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/media/test-drivers/vimc/vimc-capture.c b/drivers/media/test-drivers/vimc/vimc-capture.c
> index 93418cb5a139..73e5bdd17c57 100644
> --- a/drivers/media/test-drivers/vimc/vimc-capture.c
> +++ b/drivers/media/test-drivers/vimc/vimc-capture.c
> @@ -28,7 +28,6 @@ struct vimc_cap_device {
>  	spinlock_t qlock;
>  	struct mutex lock;
>  	u32 sequence;
> -	struct vimc_stream stream;
>  	struct media_pad pad;
>  };
>  
> @@ -241,19 +240,25 @@ static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
>  {
>  	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>  	struct media_entity *entity = &vcap->vdev.entity;
> +	struct media_pipeline *pipe = NULL;
> +	struct vimc_stream *stream;
>  	int ret;
>  
>  	atomic_inc(&vcap->ved.use_count);
>  	vcap->sequence = 0;
>  
> +	stream = kzalloc(sizeof(*stream), GFP_ATOMIC);
> +	kref_init(&stream->refcount);
> +	pipe = &stream->pipe;
> +
>  	/* Start the media pipeline */
> -	ret = media_pipeline_start(entity, &vcap->stream.pipe);
> +	ret = media_pipeline_start(entity, pipe);
>  	if (ret) {
>  		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>  		return ret;
>  	}
>  
> -	ret = vimc_streamer_s_stream(&vcap->stream, &vcap->ved, 1);
> +	ret = vimc_streamer_s_stream(stream, &vcap->ved, 1);
>  	if (ret) {
>  		media_pipeline_stop(entity);
>  		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
> @@ -270,9 +275,11 @@ static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
>  static void vimc_cap_stop_streaming(struct vb2_queue *vq)
>  {
>  	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +	struct media_pipeline *pipe = vcap->ved.ent->pipe;
> +	struct vimc_stream *stream = container_of(pipe, struct vimc_stream, pipe);

In fact, I see it's stored as part of the 'pipe' so there is one
vimc_stream per pipeline ...

So it could just be a structure on the pipe rather than obtaining a
pointer here.

I think it's probably 'ok' to have one streamer per pipe currently as
the raw input node is not functional, but I also thought that by having
the streamer as part of the sensor entity then there is one streamer
('one thread') per video source ... which would prevent this having to
be changed if someone later deals with the video node that allows
re-processing raw frames ?



>  	atomic_dec(&vcap->ved.use_count);
> -	vimc_streamer_s_stream(&vcap->stream, &vcap->ved, 0);
> +	vimc_streamer_s_stream(stream, &vcap->ved, 0);
>  
>  	/* Stop the media pipeline */
>  	media_pipeline_stop(&vcap->vdev.entity);
> diff --git a/drivers/media/test-drivers/vimc/vimc-streamer.c b/drivers/media/test-drivers/vimc/vimc-streamer.c
> index f5c9e2f3bbcb..fade37bee26d 100644
> --- a/drivers/media/test-drivers/vimc/vimc-streamer.c
> +++ b/drivers/media/test-drivers/vimc/vimc-streamer.c
> @@ -20,18 +20,13 @@
>   * Erases values of stream struct and terminates the thread
>   *
>   */
> -static void vimc_streamer_pipeline_terminate(struct vimc_stream *stream)
> +static void vimc_streamer_pipeline_terminate(struct kref *ref)
>  {
> -	struct vimc_ent_device *ved;
> -
> -	while (stream->pipe_size) {
> -		stream->pipe_size--;
> -		ved = stream->ved_pipeline[stream->pipe_size];
> -		stream->ved_pipeline[stream->pipe_size] = NULL;
> -	}
> +	struct vimc_stream *stream = container_of(ref, struct vimc_stream, refcount);
>  
>  	kthread_stop(stream->kthread);
>  	stream->kthread = NULL;
> +	kfree(stream);
>  }
>  
>  /**
> @@ -202,7 +197,7 @@ static int vimc_streamer_pipeline_init(struct vimc_stream *stream,
>  	}
>  
>  	vimc_streamer_stream_terminate(cved);
> -	vimc_streamer_pipeline_terminate(stream);
> +	kref_put(&stream->refcount, vimc_streamer_pipeline_terminate);
>  	return -EINVAL;
>  }
>  
> @@ -298,7 +293,7 @@ int vimc_streamer_s_stream(struct vimc_stream *stream,
>  			ret = PTR_ERR(stream->kthread);
>  			dev_err(ved->dev, "kthread_run failed with %d\n", ret);
>  			vimc_streamer_stream_terminate(ved);
> -			vimc_streamer_pipeline_terminate(stream);
> +			kref_put(&stream->refcount, vimc_streamer_pipeline_terminate);
>  		}
>  
>  	} else {
> @@ -306,7 +301,7 @@ int vimc_streamer_s_stream(struct vimc_stream *stream,
>  			goto out;
>  
>  		vimc_streamer_stream_terminate(ved);
> -		vimc_streamer_pipeline_terminate(stream);
> +		kref_put(&stream->refcount, vimc_streamer_pipeline_terminate);
>  	}
>  out:
>  	mutex_unlock(&vimc_streamer_lock);
> diff --git a/drivers/media/test-drivers/vimc/vimc-streamer.h b/drivers/media/test-drivers/vimc/vimc-streamer.h
> index 3bb6731b8d4d..533c88675362 100644
> --- a/drivers/media/test-drivers/vimc/vimc-streamer.h
> +++ b/drivers/media/test-drivers/vimc/vimc-streamer.h
> @@ -18,6 +18,7 @@
>  /**
>   * struct vimc_stream - struct that represents a stream in the pipeline
>   *
> + * @refcount:		kref object associated with stream struct

What does it track though?

We know it's associated with the stream struct because it's in the
vimc_stream struct.



>   * @pipe:		the media pipeline object associated with this stream
>   * @ved_pipeline:	array containing all the entities participating in the
>   * 			stream. The order is from a video device (usually a

The fact that this comment still says "all entities participating in the
stream" worries me a little, as I think now the Streamer is dealing with
multiple streams.

I think we need to be really clear with the differences of objects and
terminology.

For instance I think the current terms are something like this:

Streamer: Responsible for managing processing from a sensor device
through all entities.

Stream: A flow of frames to a single capture video device node.

Pipeline: All entities used within the vimc streamer ?

(I'm not sure if those are right, I'm writing down what my current
interpretations are, so if someone wants to/can clarify - please do).



> @@ -32,6 +33,7 @@
>   * process frames for the stream.
>   */
>  struct vimc_stream {
> +	struct kref refcount;
>  	struct media_pipeline pipe;
>  	struct vimc_ent_device *ved_pipeline[VIMC_STREAMER_PIPELINE_MAX_SIZE];
>  	unsigned int pipe_size;
> 

-- 
Regards
--
Kieran

  reply	other threads:[~2020-09-02 10:29 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-19 18:04 [PATCH v3 0/9] media: vimc: Multiple stream support in vimc Kaaira Gupta
2020-08-19 18:04 ` [PATCH v3 1/9] media: vimc: Move get_source_entity to vimc-common Kaaira Gupta
2020-08-20 15:32   ` Kieran Bingham
2020-08-19 18:04 ` [PATCH v3 2/9] media: vimc: Add get_frame callback Kaaira Gupta
2020-08-20 15:36   ` Kieran Bingham
2020-09-12 10:01     ` Kaaira Gupta
2020-10-02 11:08     ` Dafna Hirschfeld
2020-08-19 18:04 ` [PATCH v3 3/9] media: vimc: Add usage count to subdevices Kaaira Gupta
2020-10-02 11:13   ` Dafna Hirschfeld
2020-08-19 18:04 ` [PATCH v3 4/9] media: vimc: Separate starting stream from pipeline initialisation Kaaira Gupta
2020-08-21 15:11   ` Dafna Hirschfeld
2020-08-21 21:01     ` Kaaira Gupta
2020-08-28 20:37       ` Dafna Hirschfeld
2020-09-02  9:56         ` Kieran Bingham
2020-09-12 10:21           ` Kaaira Gupta
2020-09-12 10:16         ` Kaaira Gupta
2020-08-19 18:04 ` [PATCH v3 5/9] media: vimc: Separate closing of stream and thread Kaaira Gupta
2020-09-02 10:13   ` Kieran Bingham
2020-09-12 10:28     ` Kaaira Gupta
2020-08-19 18:04 ` [PATCH v3 6/9] media: vimc: Serialize vimc_streamer_s_stream() Kaaira Gupta
2020-08-19 18:04 ` [PATCH v3 7/9] media: vimc: Dynamically allocate stream struct Kaaira Gupta
2020-09-02 10:29   ` Kieran Bingham [this message]
2020-09-12 10:39     ` Kaaira Gupta
2020-08-19 18:04 ` [PATCH v3 8/9] media: vimc: Join pipeline if one already exists Kaaira Gupta
2020-09-02 10:40   ` Kieran Bingham
2020-08-19 18:04 ` [PATCH v3 9/9] media: vimc: Run multiple captures on same thread Kaaira Gupta
2020-09-02 10:46   ` Kieran Bingham
2020-09-12 10:45     ` Kaaira Gupta
2020-09-02 10:51 ` [PATCH v3 0/9] media: vimc: Multiple stream support in vimc Kieran Bingham
2020-09-12 10:49   ` Kaaira Gupta

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=7300d7ab-2be0-a6c6-b506-5af8b4a9b893@ideasonboard.com \
    --to=kieran.bingham@ideasonboard.com \
    --cc=helen.koike@collabora.com \
    --cc=kgupta@es.iitr.ac.in \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=skhan@linuxfoundation.org \
    --subject='Re: [PATCH v3 7/9] media: vimc: Dynamically allocate stream struct' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).