ALSA: usb-audio: Clean up mixer element list traverse
Introduce a new macro for iterating over mixer element list for
avoiding the open codes in many places. Also the open-coded
container_of() and the forced cast to struct usb_mixer_elem_info are
replaced with another simple macro, too.
No functional changes but just readability improvement.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 4377374..1b94387 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1172,7 +1172,7 @@
int unitid = 12; /* SamleRate ExtensionUnit ID */
list_for_each_entry(mixer, &chip->mixer_list, list) {
- cval = (struct usb_mixer_elem_info *)mixer->id_elems[unitid];
+ cval = mixer_elem_list_to_info(mixer->id_elems[unitid]);
if (cval) {
snd_usb_mixer_set_ctl_value(cval, UAC_SET_CUR,
cval->control << 8,