ALSA: timer: add config item to export PCM timer disabling for expert

PCM timer is not always used. For embedded device, we need an interface
to disable it when it is not needed, to shrink the kernel size and
memory footprint, here add CONFIG_SND_PCM_TIMER for it.

When both CONFIG_SND_PCM_TIMER and CONFIG_SND_TIMER is unselected,
about 25KB saving bonus we can get.

Please be noted that when disabled, those stubs who using pcm timer
(e.g. dmix, dsnoop & co) may work incorrectlly.

Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jie Yang <yang.jie@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 7d45645f10ba..6dc4277937b8 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1883,8 +1883,10 @@ void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
             snd_pcm_update_hw_ptr0(substream, 1) < 0)
                 goto _end;
 
+#ifdef CONFIG_SND_PCM_TIMER
         if (substream->timer_running)
                 snd_timer_interrupt(substream->timer, 1);
+#endif
  _end:
         snd_pcm_stream_unlock_irqrestore(substream, flags);
         if (runtime->transfer_ack_end)