On Wed, 10 Jun 2015 20:23:01 +0200 Takashi Iwai wrote: > From: Takashi Iwai <ti...@suse.de> > Subject: [PATCH] ALSA: hda - Reduce click noise at power up > > Some machines suffer from click noises at power up with the recent > kernels, and this seems triggered at the power transition and the > immediate verb executions. As a workaround, put a short delay (10ms) > right after the D0 transition. > > There are a few places that have the same kind of delays, especially > in the resume path. I guess they can be removed (or reduced) after > this patch. But, since the delay is relatively small, let's do it > later as a cleanup. > > Reported-by: Mihai Donțu <mihai.do...@gmail.com> > Signed-off-by: Takashi Iwai <ti...@suse.de> > --- > sound/pci/hda/hda_codec.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c > index b7782212dd64..38f5509ee52f 100644 > --- a/sound/pci/hda/hda_codec.c > +++ b/sound/pci/hda/hda_codec.c > @@ -3077,6 +3077,9 @@ static unsigned int hda_set_power_state(struct > hda_codec *codec, > break; > } > > + if (power_state == AC_PWRST_D0) > + msleep(10); > + > return state; > } >
I take back my previous observations. I was at work and did not have access to headphones (one of those days). Now I'm at home, it's 1 AM, very quiet, and I notice the following: * on speakers: the click reproduces but with _very_ low amplitude; msleep(100) is unnoticeable, but msleep(10) is, barely; * on headphones: the moment I plug them I hear a loud static sound (like an old, untuned AM radio). If I play something, the static disappears. If I pause, the static returns after ~15s. -- Mihai Donțu -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
