ALSA: snd-usb: operate on given mixer interface only

When creating the mixers for an USB audio device, the current code looks
at the host interface stored in mixer->chip->ctrl_if. Change this and
rather keep a local pointer to the interface that was given when
snd_usb_create_mixer() was called.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-by: Nicolai Krakowiak <nicolai.krakowiak@gmail.com>
Reported-by: Lean-Yves LENHOF <jean-yves@lenhof.eu.org>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Cc: stable@kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 9 insertions, 12 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index ee9aa087d8b5..c04d7c71ac88 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1939,15 +1939,13 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
         struct mixer_build state;
         int err;
         const struct usbmix_ctl_map *map;
-        struct usb_host_interface *hostif;
         void *p;
 
-        hostif = mixer->chip->ctrl_intf;
         memset(&state, 0, sizeof(state));
         state.chip = mixer->chip;
         state.mixer = mixer;
-        state.buffer = hostif->extra;
-        state.buflen = hostif->extralen;
+        state.buffer = mixer->hostif->extra;
+        state.buflen = mixer->hostif->extralen;
 
         /* check the mapping table */
         for (map = usbmix_ctl_maps; map->id; map++) {
@@ -1960,7 +1958,8 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
         }
 
         p = NULL;
-        while ((p = snd_usb_find_csint_desc(hostif->extra, hostif->extralen, p, UAC_OUTPUT_TERMINAL)) != NULL) {
+        while ((p = snd_usb_find_csint_desc(mixer->hostif->extra, mixer->hostif->extralen,
+                                            p, UAC_OUTPUT_TERMINAL)) != NULL) {
                 if (mixer->protocol == UAC_VERSION_1) {
                         struct uac1_output_terminal_descriptor *desc = p;
 
@@ -2167,17 +2166,15 @@ int snd_usb_mixer_activate(struct usb_mixer_interface *mixer)
 /* create the handler for the optional status interrupt endpoint */
 static int snd_usb_mixer_status_create(struct usb_mixer_interface *mixer)
 {
-        struct usb_host_interface *hostif;
         struct usb_endpoint_descriptor *ep;
         void *transfer_buffer;
         int buffer_length;
         unsigned int epnum;
 
-        hostif = mixer->chip->ctrl_intf;
         /* we need one interrupt input endpoint */
-        if (get_iface_desc(hostif)->bNumEndpoints < 1)
+        if (get_iface_desc(mixer->hostif)->bNumEndpoints < 1)
                 return 0;
-        ep = get_endpoint(hostif, 0);
+        ep = get_endpoint(mixer->hostif, 0);
         if (!usb_endpoint_dir_in(ep) || !usb_endpoint_xfer_int(ep))
                 return 0;
 
@@ -2207,7 +2204,6 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif,
         };
         struct usb_mixer_interface *mixer;
         struct snd_info_entry *entry;
-        struct usb_host_interface *host_iface;
         int err;
 
         strcpy(chip->card->mixername, "USB Mixer");
@@ -2224,8 +2220,8 @@ int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif,
                 return -ENOMEM;
         }
 
-        host_iface = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
-        switch (get_iface_desc(host_iface)->bInterfaceProtocol) {
+        mixer->hostif = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
+        switch (get_iface_desc(mixer->hostif)->bInterfaceProtocol) {
         case UAC_VERSION_1:
         default:
                 mixer->protocol = UAC_VERSION_1;
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index ae1a14dcfe82..81b2d8a32fb0 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -3,6 +3,7 @@
 
 struct usb_mixer_interface {
         struct snd_usb_audio *chip;
+        struct usb_host_interface *hostif;
         struct list_head list;
         unsigned int ignore_ctl_error;
         struct urb *urb;