Re: Tearing down DMA transfer setup after DMA client has finished

From: Vinod Koul
Date: Fri Dec 09 2016 - 12:54:31 EST


On Fri, Dec 09, 2016 at 05:28:01PM +0000, Måns Rullgård wrote:
> Vinod Koul <vinod.koul@xxxxxxxxx> writes:
>
> > On Fri, Dec 09, 2016 at 11:25:57AM +0100, Sebastian Frias wrote:
> >>
> >> What concrete solution do you propose?
> >
> > I have already proposed two solutions.
> >
> > A) Request a channel only when you need it. Obviously we can't do virtual
> > channels with this (though we should still use virt-channels framework).
> > The sbox setup and teardown can be done as part of channel request and
> > freeup. PL08x already does this.
> >
> > Downside is that we can only have as many consumers at a time as channels.
> >
> > I have not heard any technical reason for not doing this apart from drivers
> > grab the channel at probe, which is incorrect and needs to be fixed
> > irrespective of the problem at hand.
> >
> > This is my preferred option.
>
> Sorry, but this is not acceptable.

without outlining why..

>
> > B) Create a custom driver specific API. This API for example:
> > sbox_setup(bool enable, ...)
> > can be called by client to explicitly setup and clear up the sbox setting.
> >
> > This way we can have transactions muxed.
> >
> > I have not heard any arguments on why we shouldn't do this except Russell's
> > comment that A) solves this.
>
> Driver-specific interfaces are not the solution. That way lies chaos
> and madness.

Yes fair enough. So would API change which 99% world doesnt need.

> This would all be so much easier if you all would just shut up for a
> moment and let me fix it properly.

Oh please go away, noone is asking you to reply!

--
~Vinod