[alsa-devel] [PATCH] ALSA : hda - bug fix on return value check when getting supported power states of a codec

Lin, Mengdong mengdong.lin at intel.com
Fri Aug 10 11:15:51 CEST 2012

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 "Supported Power States", thanks!

Signed-off-by: Mengdong Lin <mengdong.lin at intel.com>
sound/pci/hda/hda_codec.c |    2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index 88a9c20..629131a 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -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;

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