[alsa-devel] [PATCH 2/7] ALSA: core: add .update_appl_ptr callback for pcm ops

[Vinod Koul]

On Fri, Sep 30, 2016 at 08:38:38PM +0200, Takashi Iwai wrote:
> On Fri, 30 Sep 2016 19:20:10 +0200,
> Vinod Koul wrote:
> > 
> > On Fri, Sep 30, 2016 at 03:24:59PM +0200, Takashi Iwai wrote:
> > > On Fri, 30 Sep 2016 14:43:25 +0200,
> > > Subhransu S. Prusty wrote:
> > > > 
> > > > From: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> > > > 
> > > > When appl_ptr is updated let low-level driver know, e.g.  to let the
> > > > low-level driver/hardware pre-fetch data opportunistically.
> > > > 
> > > > The existing .ack callback could be used but it would need to be
> > > > extended with new arguments, resulting in multiple changes in legacy
> > > > code.
> > > 
> > > I wouldn't mind changing these callers.  They aren't so many, after
> > > all. 
> > 
> > Yes this was one of the discussions we had in the past. I don't recall the
> > conclusion so had recommened to keep as is and discuss here.
> > 
> > Do you think it's better to do that or use a new one :)
> 
> It's OK to change ack callback, and actually it'll be cleaner.
> But then it'll be a problem in the next patch, I suppose :)

Yes and one of the reason is that we are using one flag to advertise two
capabilities, one is no rewind and second is appl_ptr update.

We feel we should deal with them by using two flags so that code can be
made cleaner.

Thanks
-- 
~Vinod