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

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
Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2016-04-17 09:39:41 +02:00
parent c44da62b55
commit 50fd4987c4
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
sound/pci/hda/hda_generic.c
View File

@ -826,7 +826,7 @@ static hda_nid_t path_power_update(struct hda_codec *codec,
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(struct hda_codec *codec,
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;