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ALSA : hda - bug fix on checking the supported power states of a codec 

The return value of snd_hda_param_read() is -1 for an error, otherwise
it's the supported power states of a codec.

The supported power states is a 32-bit value. Bit 31 will be set to 1
if the codec supports EPSS, thus making "sup" negative. And the bit
28:5 is reserved as "0".
So a negative value other than -1 shall be further checked.

Please refer to High-Definition spec 7.3.4.12 "Supported Power
States", thanks!

Signed-off-by: Mengdong Lin <mengdong.lin@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Mengdong Lin 2012-08-10 14:11:58 +02:00 committed by Takashi Iwai
parent 14bc9c6dc6
commit e037cb4a54
1 changed files with 1 additions and 1 deletions
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2
sound/pci/hda/hda_codec.c
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@ -3497,7 +3497,7 @@ static bool snd_hda_codec_get_supported_ps(struct hda_codec *codec, hda_nid_t fg
{
int sup = snd_hda_param_read(codec, fg, AC_PAR_POWER_STATE);
if (sup < 0)
if (sup == -1)
return false;
if (sup & power_state)
return true;