[alsa-devel] [PATCH 1/2] ALSA: pcm: Allow nonatomic trigger operations

[Takashi Iwai]

At Tue, 02 Sep 2014 15:27:47 +0300,
Jarkko Nikula wrote:
> 
> On 09/01/2014 03:00 PM, Takashi Iwai wrote:
> > Currently, many PCM operations are performed in a critical section
> > protected by spinlock, typically the trigger and pointer callbacks are
> > assumed to be atomic.  This is basically because some trigger action
> > (e.g. PCM stop after drain or xrun) is done in the interrupt handler.
> > If a driver runs in a threaded irq, however, this doesn't have to be
> > atomic.  And many devices want to handle trigger in a non-atomic
> > context due to lengthy communications.
> >
> > This patch tries all PCM calls operational in non-atomic context.
> > What it does is very simple: replaces the substream spinlock with the
> > corresponding substream mutex when pcm->nonatomic flag is set.  The
> > driver that wants to use the non-atomic PCM ops just needs to set the
> > flag and keep the reset as is.  (Of course, it must not handle any PCM
> >
> I guess "s/reset/rest/"?

Yep.


Takashi