Re: [RFC][PATCHv2 05/12] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT flag

[Sergey Senozhatsky]

On (20/02/19 09:48), Hans Verkuil wrote:
[..]
> >  int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
> >  {
> >  	int ret = vb2_verify_memory_type(q, req->memory, req->type);
> > +	bool consistent = true;
> > +
> > +	if (req->flags & V4L2_FLAG_MEMORY_NON_CONSISTENT)
> > +		consistent = false;
> 
> There is no check against allow_cache_hints: if that's 0, then
> the V4L2_FLAG_MEMORY_NON_CONSISTENT flag should be cleared since it is
> not supported.

The check is in set_queue_consistency()

static void set_queue_consistency(struct vb2_queue *q, bool consistent_mem)
{
	if (!q->allow_cache_hints)
		return;

	if (consistent_mem)
		q->dma_attrs &= ~DMA_ATTR_NON_CONSISTENT;
	else
		q->dma_attrs |= DMA_ATTR_NON_CONSISTENT;
}

I don't explicitly clear DMA_ATTR_NON_CONSISTENT attr for
!->allow_cache_hints queues just in case if the driver for
some reason sets that flag. ->allow_cache_hints is, thus,
only for cases when user-space asks us to set or clear it.

	-ss