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

[Jerry-ch Chen <Jerry-ch.Chen@mediatek.com>]

Hi Tomasz,

On Thu, 2020-05-21 at 17:11 +0000, Tomasz Figa wrote:
> 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>
> 
Ok, I've added it in the commit message.

Thanks and Best regards,
Jerry

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