Re: [PATCH 05/28] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT

[Christoph Hellwig]

On Wed, Aug 19, 2020 at 01:16:51PM +0200, Tomasz Figa wrote:
> Hi Christoph,
> 
> On Wed, Aug 19, 2020 at 8:56 AM Christoph Hellwig <hch@xxxxxx> wrote:
> >
> > The V4L2-FLAG-MEMORY-NON-CONSISTENT flag is entirely unused,
> 
> Could you explain what makes you think it's unused? It's a feature of
> the UAPI generally supported by the videobuf2 framework and relied on
> by Chromium OS to get any kind of reasonable performance when
> accessing V4L2 buffers in the userspace.

Because it doesn't do anything except on PARISC and non-coherent MIPS,
so by definition it isn't used by any of these media drivers.