Re: [PATCH 8/8] WIP: add a dma_alloc_contiguous API

[Tomasz Figa]

On Wed, Oct 7, 2020 at 8:21 AM Christoph Hellwig <hch@xxxxxx> wrote:
>
> On Tue, Oct 06, 2020 at 10:56:04PM +0200, Tomasz Figa wrote:
> > > Yes.  And make sure the API isn't implemented when VIVT caches are
> > > used, but that isn't really different from the current interface.
> >
> > Okay, thanks. Let's see if we can make necessary changes to the videobuf2.
> >
> > +Sergey Senozhatsky for awareness too.
>
> I can defer the changes a bit to see if you'd really much prefer
> the former interface.  I think for now the most important thing is
> that it works properly for the potential users, and the prime one is
> videobuf2 for now.  drm also seems like a big potential users, but I
> had a really hard time getting the developers to engage in API
> development.

My initial feeling is that it should work, but we'll give you a
definitive answer once we prototype it. :)

We might actually give it a try in the USB HCD subsystem as well, to
implement usb_alloc_noncoherent(), as an optimization for drivers
which have to perform multiple random accesses to the URB buffers. I
think you might recall discussing this by the way of the pwc and
uvcvideo camera drivers.

Best regards,
Tomasz