linux-kernel - Re: Audio crackles with 4.1-rc1

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Date:	Tue, 19 May 2015 08:15:32 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Jonathan McDowell <noodles@...th.li>
Cc:	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: Audio crackles with 4.1-rc1

At Sat, 2 May 2015 16:05:13 +0100,
Jonathan McDowell wrote:
> 
> On Thu, Apr 30, 2015 at 07:06:31PM +0200, Takashi Iwai wrote:
> > At Thu, 30 Apr 2015 16:01:31 +0100, Jonathan McDowell wrote:
> > > 
> > > On Wed, Apr 29, 2015 at 01:54:57PM +0200, Takashi Iwai wrote:
> > > > 
> > > > One patch you can try (with or without power_save_node
> > > > disablement) is below, it squashes the verb sequences at (runtime)
> > > > PM resume as we did for 4.0.  Let me know if this changes the
> > > > behavior.
> > > 
> > > Patch alone has no effect. Patch with power_save_node disablement
> > > solves the problem. Didn't try power_save_node disablement without
> > > the patch.
> > 
> > Then please confirm that only power_save_node disablement suffices.
> > This can be considered as the least change that can be put to 4.1-rc
> > if no better fix is found.
> 
> Setting codec->power_save_node to 0 in patch_alc269 is sufficient; no
> noticeable cracking occurring.

Does the patch below have any improvement?


Takashi

---
diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
index 788f969b1a68..17147c2638f3 100644
--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -841,11 +841,19 @@ static hda_nid_t path_power_update(struct hda_codec *codec,
 		else
 			state = AC_PWRST_D3;
 		if (!snd_hda_check_power_state(codec, nid, state)) {
-			snd_hda_codec_write(codec, nid, 0,
+			snd_hda_codec_read(codec, nid, 0,
 					    AC_VERB_SET_POWER_STATE, state);
 			changed = nid;
-			if (state == AC_PWRST_D0)
-				snd_hdac_regmap_sync_node(&codec->core, nid);
+			if (state == AC_PWRST_D0) {
+				msleep(10);
+				/* all known codecs seem to be capable to handle
+				 * widgets state even in D3, so far.
+				 * if any new codecs need to restore the widget
+				 * states after D0 transition, call the function
+				 * below.
+				 */
+				/* snd_hdac_regmap_sync_node(&codec->core, nid); */
+			}
 		}
 	}
 	return changed;
--
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