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

[Hans Verkuil <hverkuil@xs4all.nl>]

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@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?

Yes, this looks good.

Sorry for the late reply.

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

Regards,

	Hans