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

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On Wed, Jun 10, 2020 at 12:29 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
>
> On 21/05/2020 19:11, Tomasz Figa wrote:
> > Hi Jerry,
> >
> > On Wed, Dec 04, 2019 at 08:47:29PM +0800, Jerry-ch Chen wrote:
> >> From: Pi-Hsun Shih <pihsun@xxxxxxxxxxxx>
> >>
> >> 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@xxxxxxxxxxxx>
> >> Signed-off-by: Jerry-ch Chen <jerry-ch.chen@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
> >> ---
> >>  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@xxxxxxxxxxxx>
> >
> > [Corrected Hans's email address.]
> > Hans, does this look good to you?
>
> Yes, this looks good.
>
> Sorry for the late reply.

No worries! Thanks a lot.

>
> I assume this will be part of a future patch series that calls these new functions?

The mtk-jpeg encoder series depends on this patch as well, so I guess
it would go together with whichever is ready first.

I would also envision someone changing the other existing drivers to
use the helpers, as I'm pretty much sure some of them don't handle
suspend/resume correctly.

Best regards,
Tomasz



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