Patch "ALSA: hda - Don't trust the reported actual power state" has been added to the 4.5-stable tree

Patch "ALSA: hda - Don't trust the reported actual power state" has been added to the 4.5-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ALSA: hda - Don't trust the reported actual power state

to the 4.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     alsa-hda-don-t-trust-the-reported-actual-power-state.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 50fd4987c4f3c3ebf0ce94d932732011bbdc7c71 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Sun, 17 Apr 2016 09:39:41 +0200
Subject: ALSA: hda - Don't trust the reported actual power state

From: Takashi Iwai <tiwai@suse.de>

commit 50fd4987c4f3c3ebf0ce94d932732011bbdc7c71 upstream.

We've got a regression report that the recording on Mac with a cirrus
codec doesn't work any longer.  This turned out to be the missing
power up to D0 by power_save_node enablement.

After analyzing the traces, we found out that the culprit is that the
codec advertises the "actual" power state of a few nodes to be D0
while the "target" power state is D3.  This inconsistency is usually
OK, as it implies the power transition.  But in the case of cirrus
codec, this seems to be stuck to D3 while it's not actually D0.

This patch addresses the issue by checking the power state difference
more strictly.  It sends the power-state change verb unless both the
target and the actual power states show the given value.

We may introduce yet another flag indicating the possible broken
hardware power state, but it's anyway safer to set the proper power
state even in a transition (at least it's harmless as long as the
target state is same).  So this simpler change was applied now.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=116171
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 sound/pci/hda/hda_generic.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -826,7 +826,7 @@ static hda_nid_t path_power_update(struc
 				   bool allow_powerdown)
 {
 	hda_nid_t nid, changed = 0;
-	int i, state;
+	int i, state, power;
 
 	for (i = 0; i < path->depth; i++) {
 		nid = path->path[i];
@@ -838,7 +838,9 @@ static hda_nid_t path_power_update(struc
 			state = AC_PWRST_D0;
 		else
 			state = AC_PWRST_D3;
-		if (!snd_hda_check_power_state(codec, nid, state)) {
+		power = snd_hda_codec_read(codec, nid, 0,
+					   AC_VERB_GET_POWER_STATE, 0);
+		if (power != (state | (state << 4))) {
 			snd_hda_codec_write(codec, nid, 0,
 					    AC_VERB_SET_POWER_STATE, state);
 			changed = nid;


Patches currently in stable-queue which might be from tiwai@suse.de are

queue-4.5/alsa-pcxhr-fix-missing-mutex-unlock.patch
queue-4.5/alsa-hda-add-dock-support-for-thinkpad-x260.patch
queue-4.5/alsa-hda-keep-powering-up-adcs-on-cirrus-codecs.patch
queue-4.5/alsa-hda-update-bclk-also-at-hotplug-for-i915-hsw-bdw.patch
queue-4.5/alsa-hda-add-pci-id-for-intel-broxton-t.patch
queue-4.5/alsa-hda-don-t-trust-the-reported-actual-power-state.patch
queue-4.5/alsa-hda-realtek-add-alc3234-headset-mode-for-optiplex-9020m.patch