[3.16.y-ckt stable] Patch "ALSA: hda - Fix regression of HD-audio controller fallback modes" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ALSA: hda - Fix regression of HD-audio controller fallback modes

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 77198b34cf07bb69aa8add772d91931edad2bc32 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Sun, 8 Mar 2015 18:29:50 +0100
Subject: ALSA: hda - Fix regression of HD-audio controller fallback modes

commit a1f3f1ca66bd12c339b17a0c2ef93a093f90a277 upstream.

The commit [63e51fd708f5: ALSA: hda - Don't take unresponsive D3
transition too serious] introduced a conditional fallback behavior to
the HD-audio controller depending on the flag set.  However, it
introduced a silly bug, too, that the flag was evaluated in a reverse
way.  This resulted in a regression of HD-audio controller driver
where it can't go to the fallback mode at communication errors.

Unfortunately (or fortunately?) this didn't come up until recently
because the affected code path is an error handling that happens only
on an unstable hardware chip.  Most of recent chips work stably, thus
they didn't hit this problem.  Now, we've got a regression report with
a VIA chip, and this seems indeed requiring the fallback to the
polling mode, and finally the bug was revealed.

The fix is a oneliner to remove the wrong logical NOT in the check.
(Lesson learned - be careful about double negation.)

The bug should be backported to stable, but the patch won't be
applicable to 3.13 or earlier because of the code splits.  The stable
fix patches for earlier kernels will be posted later manually.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94021
Fixes: 63e51fd708f5 ('ALSA: hda - Don't take unresponsive D3 transition too serious')
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 sound/pci/hda/hda_controller.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
index e476a198c15f..c6136597785a 100644
--- a/sound/pci/hda/hda_controller.c
+++ b/sound/pci/hda/hda_controller.c
@@ -1244,7 +1244,7 @@ static unsigned int azx_rirb_get_response(struct hda_bus *bus,
 		}
 	}

-	if (!bus->no_response_fallback)
+	if (bus->no_response_fallback)
 		return -1;

 	if (!chip->polling_mode && chip->poll_count < 2) {