Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 14790f1c authored by Takashi Iwai's avatar Takashi Iwai Committed by Jaroslav Kysela
Browse files

[ALSA] Test volume resolution of usb audio at initialization 



Test the volume of usb audio whether actually it works and adjusts
the resolution value according to it.

Some USB audio devices report a lower resolution than it reacts.
The only possible check is to write and read a volume value.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 0b2dcd5d

sound/usb/usbmixer.c

+34 −3
Original line number Diff line number Diff line
@@ -306,8 +306,8 @@ static int get_relative_value(struct usb_mixer_elem_info *cval, int val) 
		cval->res = 1;

	if (val < cval->min)

		return 0;

	else if (val > cval->max)

		return (cval->max - cval->min) / cval->res;

	else if (val >= cval->max)

		return (cval->max - cval->min + cval->res - 1) / cval->res;

	else

		return (val - cval->min) / cval->res;

}
@@ -670,6 +670,36 @@ static int get_min_max(struct usb_mixer_elem_info *cval, int default_min) 
		}

		if (cval->res == 0)

			cval->res = 1;



		/* Additional checks for the proper resolution

		 *

		 * Some devices report smaller resolutions than actually

		 * reacting.  They don't return errors but simply clip

		 * to the lower aligned value.

		 */

		if (cval->min + cval->res < cval->max) {

			int last_valid_res = cval->res;

			int saved, test, check;

			get_cur_mix_value(cval, minchn, &saved);

			for (;;) {

				test = saved;

				if (test < cval->max)

					test += cval->res;

				else

					test -= cval->res;

				if (test < cval->min || test > cval->max ||

				    set_cur_mix_value(cval, minchn, test) ||

				    get_cur_mix_value(cval, minchn, &check)) {

					cval->res = last_valid_res;

					break;

				}

				if (test == check)

					break;

				cval->res *= 2;

			}

			set_cur_mix_value(cval, minchn, saved);

		}



		cval->initialized = 1;

	}

	return 0;
@@ -695,7 +725,8 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol, struct snd_ctl_ 
		if (! cval->initialized)

			get_min_max(cval,  0);

		uinfo->value.integer.min = 0;

		uinfo->value.integer.max = (cval->max - cval->min) / cval->res;

		uinfo->value.integer.max =

			(cval->max - cval->min + cval->res - 1) / cval->res;

	}

	return 0;

}