Re: [alsa-devel] [PATCH 2/2] ALSA: hda: support for wallclock timestamps

Reuse code from clocksource to handle wall clock counter. Since wrapparound occurs, the audio timestamp is reinitialized to zero on a trigger. Synchronized linked devices will start counting from same reference to avoid any drift.

@@ -2024,6 +2096,22 @@ static int azx_pcm_trigger(struct

snd_pcm_substream *substream, int cmd)

                    azx_readl(chip, OLD_SSYNC) & ~sbits);
    else
            azx_writel(chip, SSYNC, azx_readl(chip, SSYNC) & ~sbits);

•   if (start) {
  

•           azx_timecounter_init(substream, 0, 0);
  

•           if (nsync > 1) {
  

•                   cycle_t cycle_last;
  

•                   /* same start cycle for master and group */
  

•                   azx_dev = get_azx_dev(substream);
  

•                   cycle_last = azx_dev->azx_tc.cycle_last;
  

•                   snd_pcm_group_for_each_entry(s, substream) {
  

•                           if (s->pcm->card != substream->pcm->card)
  

•                                   continue;
  

•                           azx_timecounter_init(s, 1, cycle_last);
  

•                   }
  

•           }
  

•   }
    spin_unlock(&chip->reg_lock);
    return 0;
  

}

Will the timer reinitialise when multistreaming using front panel headphone , rear panel speakers , digital output and hdmi ?