Re: [PATCH v6 03/14] videobuf2: handle V4L2 buffer cache flags

From: Sergey Senozhatsky
Date: Tue Jun 02 2020 - 08:10:58 EST


On (20/06/02 12:27), Hans Verkuil wrote:
[..]
> > Sorry, Hans, do you suggest to have something like this:
> >
> > if (q->memory == VB2_MEMORY_DMABUF) {
> > vb->need_cache_sync_on_finish = 0;
> > vb->need_cache_sync_on_prepare = 0;
> > b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_INVALIDATE;
> > b->flags &= ~V4L2_BUF_FLAG_NO_CACHE_CLEAN;
> > return;
> > }
> >
> > I didn't clear the ->flags there because we clear the vb flush/sync
> > flags: ->need_cache_sync_on_finish/prepare are zeros for DMABUF memory
> > type. Which is equivalent to passing V4L2_BUF_FLAG_NO_CACHE_INVALIDATE
> > V4L2_BUF_FLAG_NO_CACHE_CLEAN. IOW we would clearing both "vb's do cache
> > sync" and request's "do not cache sync".
>
> Ah, yes. In that case the v4l-utils patch is likely wrong.
> Can you take a look at that patch?

Hans, are we talking about "v4l2-utils: test cache_hints for MMAP queues"
patch? I can take a look, yes.

-ss