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.c b/sound/usb/mixer.c
index bb203b3..265258b 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2598,9 +2598,9 @@ void snd_usb_mixer_notify_id(struct usb_mixer_interface *mixer, int unitid)
 {
        struct usb_mixer_elem_list *list;
 
-       for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem) {
+       for_each_mixer_elem(list, mixer, unitid) {
                struct usb_mixer_elem_info *info =
-                       (struct usb_mixer_elem_info *)list;
+                       mixer_elem_list_to_info(list);
                /* invalidate cache, so the value is read from the device */
                info->cached = 0;
                snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
@@ -2611,7 +2611,7 @@ void snd_usb_mixer_notify_id(struct usb_mixer_interface *mixer, int unitid)
 static void snd_usb_mixer_dump_cval(struct snd_info_buffer *buffer,
                                    struct usb_mixer_elem_list *list)
 {
-       struct usb_mixer_elem_info *cval = (struct usb_mixer_elem_info *)list;
+       struct usb_mixer_elem_info *cval = mixer_elem_list_to_info(list);
        static char *val_types[] = {"BOOLEAN", "INV_BOOLEAN",
                                    "S8", "U8", "S16", "U16"};
        snd_iprintf(buffer, "    Info: id=%i, control=%i, cmask=0x%x, "
@@ -2637,8 +2637,7 @@ static void snd_usb_mixer_proc_read(struct snd_info_entry *entry,
                                mixer->ignore_ctl_error);
                snd_iprintf(buffer, "Card: %s\n", chip->card->longname);
                for (unitid = 0; unitid < MAX_ID_ELEMS; unitid++) {
-                       for (list = mixer->id_elems[unitid]; list;
-                            list = list->next_id_elem) {
+                       for_each_mixer_elem(list, mixer, unitid) {
                                snd_iprintf(buffer, "  Unit: %i\n", list->id);
                                if (list->kctl)
                                        snd_iprintf(buffer,
@@ -2668,19 +2667,19 @@ static void snd_usb_mixer_interrupt_v2(struct usb_mixer_interface *mixer,
                return;
        }
 
-       for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem)
+       for_each_mixer_elem(list, mixer, unitid)
                count++;
 
        if (count == 0)
                return;
 
-       for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem) {
+       for_each_mixer_elem(list, mixer, unitid) {
                struct usb_mixer_elem_info *info;
 
                if (!list->kctl)
                        continue;
 
-               info = (struct usb_mixer_elem_info *)list;
+               info = mixer_elem_list_to_info(list);
                if (count > 1 && info->control != control)
                        continue;
 
@@ -2946,7 +2945,7 @@ int snd_usb_mixer_suspend(struct usb_mixer_interface *mixer)
 
 static int restore_mixer_value(struct usb_mixer_elem_list *list)
 {
-       struct usb_mixer_elem_info *cval = (struct usb_mixer_elem_info *)list;
+       struct usb_mixer_elem_info *cval = mixer_elem_list_to_info(list);
        int c, err, idx;
 
        if (cval->cmask) {
@@ -2982,8 +2981,7 @@ int snd_usb_mixer_resume(struct usb_mixer_interface *mixer, bool reset_resume)
        if (reset_resume) {
                /* restore cached mixer values */
                for (id = 0; id < MAX_ID_ELEMS; id++) {
-                       for (list = mixer->id_elems[id]; list;
-                            list = list->next_id_elem) {
+                       for_each_mixer_elem(list, mixer, id) {
                                if (list->resume) {
                                        err = list->resume(list);
                                        if (err < 0)

diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index ba27f7a..e026534 100644 (file)
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -53,6 +53,12 @@ struct usb_mixer_elem_list {
        usb_mixer_elem_resume_func_t resume;
 };
 
+/* iterate over mixer element list of the given unit id */
+#define for_each_mixer_elem(list, mixer, id)   \
+       for ((list) = (mixer)->id_elems[id]; (list); (list) = (list)->next_id_elem)
+#define mixer_elem_list_to_info(list) \
+       container_of(list, struct usb_mixer_elem_info, head)
+
 struct usb_mixer_elem_info {
        struct usb_mixer_elem_list head;
        unsigned int control;   /* CS or ICN (high byte) */

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 4377374..1b94387 100644 (file)
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1172,7 +1172,7 @@ void snd_emuusb_set_samplerate(struct snd_usb_audio *chip,
        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,

diff --git a/sound/usb/mixer_scarlett.c b/sound/usb/mixer_scarlett.c
index c33e237..4aeb948 100644 (file)
--- a/sound/usb/mixer_scarlett.c
+++ b/sound/usb/mixer_scarlett.c
@@ -287,8 +287,7 @@ static int scarlett_ctl_switch_put(struct snd_kcontrol *kctl,
 
 static int scarlett_ctl_resume(struct usb_mixer_elem_list *list)
 {
-       struct usb_mixer_elem_info *elem =
-               container_of(list, struct usb_mixer_elem_info, head);
+       struct usb_mixer_elem_info *elem = mixer_elem_list_to_info(list);
        int i;
 
        for (i = 0; i < elem->channels; i++)
@@ -447,8 +446,7 @@ static int scarlett_ctl_enum_put(struct snd_kcontrol *kctl,
 
 static int scarlett_ctl_enum_resume(struct usb_mixer_elem_list *list)
 {
-       struct usb_mixer_elem_info *elem =
-               container_of(list, struct usb_mixer_elem_info, head);
+       struct usb_mixer_elem_info *elem = mixer_elem_list_to_info(list);
 
        if (elem->cached)
                snd_usb_set_cur_mix_value(elem, 0, 0, *elem->cache_val);