From eedbdf03a25ab3b2c332ad7fa205aa8ffbe477ba Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Tue, 16 Jun 2009 14:27:35 +0200 Subject: [PATCH] ALSA: usb-audio - Correct bogus volume dB information Some USB devices give bogus dB information and it screws up PA. It's better to detect a broken value and correct it in the driver before exposing the value to the outside. Signed-off-by: Takashi Iwai --- sound/usb/usbmixer.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c index f127bfd97c0..539b427d08c 100644 --- a/sound/usb/usbmixer.c +++ b/sound/usb/usbmixer.c @@ -470,6 +470,15 @@ static int mixer_vol_tlv(struct snd_kcontrol *kcontrol, int op_flag, */ scale[2] = (convert_signed_value(cval, cval->min) * 100) / 256; scale[3] = (convert_signed_value(cval, cval->max) * 100) / 256; + if (scale[3] <= scale[2]) { + /* something is wrong; assume it's either from/to 0dB */ + if (scale[2] < 0) + scale[3] = 0; + else if (scale[2] > 0) + scale[2] = 0; + else /* totally crap, return an error */ + return -EINVAL; + } if (copy_to_user(_tlv, scale, sizeof(scale))) return -EFAULT; return 0; -- 2.39.5