Re: [RFC PATCH V4 1/4] media: v4l2-mem2mem: add v4l2_m2m_suspend, v4l2_m2m_resume

[Tomasz Figa <tfiga@chromium.org>]

Hi Jerry,

On Wed, Dec 04, 2019 at 08:47:29PM +0800, Jerry-ch Chen wrote:
> From: Pi-Hsun Shih <pihsun@chromium.org>
> 
> Add two functions that can be used to stop new jobs from being queued /
> continue running queued job. This can be used while a driver using m2m
> helper is going to suspend / wake up from resume, and can ensure that
> there's no job running in suspend process.
> 
> BUG=b:143046833
> TEST=build
> 
> Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
> Signed-off-by: Jerry-ch Chen <jerry-ch.chen@mediatek.corp-partner.google.com>
> ---
>  drivers/media/v4l2-core/v4l2-mem2mem.c | 40 ++++++++++++++++++++++++++
>  include/media/v4l2-mem2mem.h           | 22 ++++++++++++++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
> index 5bbdec55b7d7..76ba203e0035 100644
> --- a/drivers/media/v4l2-core/v4l2-mem2mem.c
> +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
> @@ -47,6 +47,10 @@ module_param(debug, bool, 0644);
>  #define TRANS_ABORT		(1 << 2)
>  
>  
> +/* The job queue is not running new jobs */
> +#define QUEUE_PAUSED		(1 << 0)
> +
> +
>  /* Offset base for buffers on the destination queue - used to distinguish
>   * between source and destination buffers when mmapping - they receive the same
>   * offsets but for different queues */
> @@ -88,6 +92,7 @@ static const char * const m2m_entity_name[] = {
>   * @job_queue:		instances queued to run
>   * @job_spinlock:	protects job_queue
>   * @job_work:		worker to run queued jobs.
> + * @job_queue_flags:	flags of the queue status, %QUEUE_PAUSED.
>   * @m2m_ops:		driver callbacks
>   */
>  struct v4l2_m2m_dev {
> @@ -105,6 +110,7 @@ struct v4l2_m2m_dev {
>  	struct list_head	job_queue;
>  	spinlock_t		job_spinlock;
>  	struct work_struct	job_work;
> +	unsigned long		job_queue_flags;
>  
>  	const struct v4l2_m2m_ops *m2m_ops;
>  };
> @@ -267,6 +273,12 @@ static void v4l2_m2m_try_run(struct v4l2_m2m_dev *m2m_dev)
>  		return;
>  	}
>  
> +	if (m2m_dev->job_queue_flags & QUEUE_PAUSED) {
> +		spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> +		dprintk("Running new jobs is paused\n");
> +		return;
> +	}
> +
>  	m2m_dev->curr_ctx = list_first_entry(&m2m_dev->job_queue,
>  				   struct v4l2_m2m_ctx, queue);
>  	m2m_dev->curr_ctx->job_flags |= TRANS_RUNNING;
> @@ -447,6 +459,34 @@ void v4l2_m2m_job_finish(struct v4l2_m2m_dev *m2m_dev,
>  }
>  EXPORT_SYMBOL(v4l2_m2m_job_finish);
>  
> +void v4l2_m2m_suspend(struct v4l2_m2m_dev *m2m_dev)
> +{
> +	unsigned long flags;
> +	struct v4l2_m2m_ctx *curr_ctx;
> +
> +	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
> +	m2m_dev->job_queue_flags |= QUEUE_PAUSED;
> +	curr_ctx = m2m_dev->curr_ctx;
> +	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> +
> +	if (curr_ctx)
> +		wait_event(curr_ctx->finished,
> +			   !(curr_ctx->job_flags & TRANS_RUNNING));
> +}
> +EXPORT_SYMBOL(v4l2_m2m_suspend);
> +
> +void v4l2_m2m_resume(struct v4l2_m2m_dev *m2m_dev)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&m2m_dev->job_spinlock, flags);
> +	m2m_dev->job_queue_flags &= ~QUEUE_PAUSED;
> +	spin_unlock_irqrestore(&m2m_dev->job_spinlock, flags);
> +
> +	v4l2_m2m_try_run(m2m_dev);
> +}
> +EXPORT_SYMBOL(v4l2_m2m_resume);
> +
>  int v4l2_m2m_reqbufs(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
>  		     struct v4l2_requestbuffers *reqbufs)
>  {
> diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
> index 5467264771ec..119a195da390 100644
> --- a/include/media/v4l2-mem2mem.h
> +++ b/include/media/v4l2-mem2mem.h
> @@ -183,6 +183,28 @@ v4l2_m2m_buf_done(struct vb2_v4l2_buffer *buf, enum vb2_buffer_state state)
>  	vb2_buffer_done(&buf->vb2_buf, state);
>  }
>  
> +/**
> + * v4l2_m2m_suspend() - stop new jobs from being run and wait for current job
> + * to finish
> + *
> + * @m2m_dev: opaque pointer to the internal data to handle M2M context
> + *
> + * Called by a driver in the suspend hook. Stop new jobs from being run, and
> + * wait for current running job to finish.
> + */
> +void v4l2_m2m_suspend(struct v4l2_m2m_dev *m2m_dev);
> +
> +/**
> + * v4l2_m2m_resume() - resume job running and try to run a queued job
> + *
> + * @m2m_dev: opaque pointer to the internal data to handle M2M context
> + *
> + * Called by a driver in the resume hook. This reverts the operation of
> + * v4l2_m2m_suspend() and allows job to be run. Also try to run a queued job if
> + * there is any.
> + */
> +void v4l2_m2m_resume(struct v4l2_m2m_dev *m2m_dev);
> +
>  /**
>   * v4l2_m2m_reqbufs() - multi-queue-aware REQBUFS multiplexer
>   *
> -- 
> 2.18.0

Reviewed-by: Tomasz Figa <tfiga@chromium.org>

[Corrected Hans's email address.]
Hans, does this look good to you?

Best regards,
Tomasz


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