Re: [PATCH 1/2] ALSA: firewire: process packets in 'struct snd_pcm_ops.ack' callback

[Takashi Iwai <tiwai@suse.de>]

On Fri, 09 Jun 2017 09:01:56 +0200,
Takashi Sakamoto wrote:
> 
> On Jun 9 2017 15:53, Takashi Iwai wrote:
> >>> From: Takashi Iwai <tiwai@suse.de>
> >>> Subject: [PATCH] ALSA: pcm: Suppress status/control mmap when ack ops is
> >>>   present
> >>>
> >>> The drivers using PCM ack ops require the notification whenever
> >>> appl_ptr is updated in general.  But when the PCM status/control page
> >>> is mmapped, this notification doesn't happen, per design, thus it's
> >>> not guaranteed to receive the fine-grained updates.
> >>>
> >>> For improving the situation, this patch simply suppresses the PCM
> >>> status/control mmap when ack ops is defined.  At least, for all
> >>> existing drivers with ack, this should give more benefit.
> >>>
> >>> Once when we really need the full optimization with status/control
> >>> mmap even using ack ops, we may reconsider the check, e.g. introducing
> >>> a new flag.  But, so far, this should be good enough.
> >>
> >> Yes this makes sense and we tested it for us, looks good
> >>
> >> Reveiwed-by: Vinod Koul <vinod.koul@intel.com>
> >> Tested-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
> >
> > OK, thanks.
> >
> > If Sakamato-san is happy with this change, I'm going to merge it for
> > 4.13.
> 
> I'm writing a long long message about my concern for this patch.

Better to shorten, if you want to convince someone :)

> I'm
> happy if you postpone application to your for-next branch, till next
> week.

OK.


Takashi