Re: [RFC v2 03/11] vb2: Move cache synchronisation from buffer done to dqbuf handler

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Shuah,

On Monday 27 Mar 2017 15:27:36 Shuah Khan wrote:
> On Thu, Dec 15, 2016 at 6:24 PM, Laurent Pinchart wrote:
> > From: Sakari Ailus <sakari.ailus@linux.intel.com>
> > 
> > The cache synchronisation may be a time consuming operation and thus not
> > best performed in an interrupt which is a typical context for
> > vb2_buffer_done() calls. This may consume up to tens of ms on some
> > machines, depending on the buffer size.
> > 
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> > Changes since v1:
> > 
> > - Don't rename the 'i' loop counter to 'plane'
> > ---
> > 
> >  drivers/media/v4l2-core/videobuf2-core.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/videobuf2-core.c
> > b/drivers/media/v4l2-core/videobuf2-core.c index
> > 8ba48703b189..15a83f338072 100644
> > --- a/drivers/media/v4l2-core/videobuf2-core.c
> > +++ b/drivers/media/v4l2-core/videobuf2-core.c
> > @@ -889,7 +889,6 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum
> > vb2_buffer_state state)> 
> >  {
> >         struct vb2_queue *q = vb->vb2_queue;
> >         unsigned long flags;
> > -       unsigned int plane;
> > 
> >         if (WARN_ON(vb->state != VB2_BUF_STATE_ACTIVE))
> >                 return;
> > @@ -910,10 +909,6 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum
> > vb2_buffer_state state)
> >         dprintk(4, "done processing on buffer %d, state: %d\n",
> >                         vb->index, state);
> > 
> > -       /* sync buffers */
> > -       for (plane = 0; plane < vb->num_planes; ++plane)
> > -               call_void_memop(vb, finish, vb->planes[plane].mem_priv);
> > -
> >         spin_lock_irqsave(&q->done_lock, flags);
> >         if (state == VB2_BUF_STATE_QUEUED ||
> >             state == VB2_BUF_STATE_REQUEUEING) {
> > @@ -1571,6 +1566,10 @@ static void __vb2_dqbuf(struct vb2_buffer *vb)
> > 
> >         vb->state = VB2_BUF_STATE_DEQUEUED;
> > 
> > +       /* sync buffers */
> > +       for (i = 0; i < vb->num_planes; ++i)
> > +               call_void_memop(vb, finish, vb->planes[i].mem_priv);
> > +
> 
> Does this compile?? Where is "i" defined? Looks like it needs to be added
> back in.

It's already defined at the beginning of the __vb2_dqbuf() function.

> >         /* unmap DMABUF buffer */
> >         if (q->memory == VB2_MEMORY_DMABUF)
> >                 for (i = 0; i < vb->num_planes; ++i) {

-- 
Regards,

Laurent Pinchart