[alsa-devel] [PATCH] ASoC: Intel: Bsw: Read sst DSP DMA pointer after period elapse occurs

[Fang, Yang A]

> -----Original Message-----
> From: Mark Brown [mailto:broonie at kernel.org]
> Sent: Monday, August 17, 2015 12:56 PM
> To: Fang, Yang A
> Cc: lgirdwood at gmail.com; alsa-devel at alsa-project.org;
> dgreid at chromium.org; Nujella, Sathyanarayana;
> kevin.strasser at linux.intel.com; Sripathi, Srinivas; Iriawan, Denny; Jain,
> Praveen K; Koul, Vinod; Mirche, Dinesh
> Subject: Re: [PATCH] ASoC: Intel: Bsw: Read sst DSP DMA pointer after
> period elapse occurs
> 
> On Sun, Aug 16, 2015 at 11:12:25PM -0700, yang.a.fang at intel.com wrote:
> 
> > We should not read sst hw_ptr and pcm_delay in
> > sst_platform_pcm_pointer Since it will be ricky if
> > sst_platform_pcm_pointer is called while dsp is updating the
> > timestamp.Now read sst hw_ptr after period elapse interrupt occurs.
> 
> So I guess there's still some risk that we could run into problems here if we
> take too long to service the interrupt and/or the period is very short?  Is
> there anything we can do to improve that?
Hi Mark,
 I think before and after the patch. There is no difference in term of 
 handling the period elapse interrupt . because before the patch 
 sst_period_elapsed calls the snd_pcm_period_elapsed which in turn 
 calling the sst_platform_pcm_pointer which calls the stream_read_tstamp.