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Commit eedbdf03 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

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: default avatarTakashi Iwai <tiwai@suse.de>
parent b8e1c73f

sound/usb/usbmixer.c

+9 −0
Original line number Diff line number Diff line
@@ -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;