ALSA: usb-audio: scarlett2: Remove hard-coded USB #defines

Remove the hard-coded interface number and related constants for the
vendor-specific interface and look them up from the USB endpoint
descriptor.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/20210620164652.GA9237@m.b4.vu
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c
index 45fd540..2e1937b 100644 (file)
--- a/sound/usb/mixer_scarlett_gen2.c
+++ b/sound/usb/mixer_scarlett_gen2.c
@@ -230,6 +230,10 @@ struct scarlett2_data {
        struct mutex data_mutex; /* lock access to this data */
        struct delayed_work work;
        const struct scarlett2_device_info *info;
+       __u8 bInterfaceNumber;
+       __u8 bEndpointAddress;
+       __u16 wMaxPacketSize;
+       __u8 bInterval;
        int num_mux_srcs;
        int num_mux_dsts;
        u16 scarlett2_seq;
@@ -444,12 +448,6 @@ static int scarlett2_get_port_start_num(const struct scarlett2_ports *ports,
 
 /*** USB Interactions ***/
 
-/* Vendor-Specific Interface, Endpoint, MaxPacketSize, Interval */
-#define SCARLETT2_USB_VENDOR_SPECIFIC_INTERFACE 5
-#define SCARLETT2_USB_INTERRUPT_ENDPOINT 4
-#define SCARLETT2_USB_INTERRUPT_MAX_DATA 64
-#define SCARLETT2_USB_INTERRUPT_INTERVAL 3
-
 /* Interrupt flags for dim/mute button and monitor changes */
 #define SCARLETT2_USB_NOTIFY_DIM_MUTE 0x00200000
 #define SCARLETT2_USB_NOTIFY_MONITOR  0x00400000
@@ -615,7 +613,7 @@ static int scarlett2_usb(
                        SCARLETT2_USB_VENDOR_SPECIFIC_CMD_REQ,
                        USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
                        0,
-                       SCARLETT2_USB_VENDOR_SPECIFIC_INTERFACE,
+                       private->bInterfaceNumber,
                        req,
                        req_buf_size);
 
@@ -635,7 +633,7 @@ static int scarlett2_usb(
                        SCARLETT2_USB_VENDOR_SPECIFIC_CMD_RESP,
                        USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
                        0,
-                       SCARLETT2_USB_VENDOR_SPECIFIC_INTERFACE,
+                       private->bInterfaceNumber,
                        resp,
                        resp_buf_size);
 
@@ -1886,12 +1884,45 @@ static void scarlett2_count_mux_io(struct scarlett2_data *private)
        private->num_mux_dsts = dsts;
 }
 
-/* Initialise private data and sequence number */
+/* Look through the interface descriptors for the Focusrite Control
+ * interface (bInterfaceClass = 255 Vendor Specific Class) and set
+ * bInterfaceNumber, bEndpointAddress, wMaxPacketSize, and bInterval
+ * in private
+ */
+static int scarlett2_find_fc_interface(struct usb_device *dev,
+                                      struct scarlett2_data *private)
+{
+       struct usb_host_config *config = dev->actconfig;
+       int i;
+
+       for (i = 0; i < config->desc.bNumInterfaces; i++) {
+               struct usb_interface *intf = config->interface[i];
+               struct usb_interface_descriptor *desc =
+                       &intf->altsetting[0].desc;
+               struct usb_endpoint_descriptor *epd;
+
+               if (desc->bInterfaceClass != 255)
+                       continue;
+
+               epd = get_endpoint(intf->altsetting, 0);
+               private->bInterfaceNumber = desc->bInterfaceNumber;
+               private->bEndpointAddress = epd->bEndpointAddress &
+                       USB_ENDPOINT_NUMBER_MASK;
+               private->wMaxPacketSize = le16_to_cpu(epd->wMaxPacketSize);
+               private->bInterval = epd->bInterval;
+               return 0;
+       }
+
+       return -EINVAL;
+}
+
+/* Initialise private data, sequence number, and get the USB data */
 static int scarlett2_init_private(struct usb_mixer_interface *mixer,
                                  const struct scarlett2_device_info *info)
 {
        struct scarlett2_data *private =
                kzalloc(sizeof(struct scarlett2_data), GFP_KERNEL);
+       int err;
 
        if (!private)
                return -ENOMEM;
@@ -1899,13 +1930,19 @@ static int scarlett2_init_private(struct usb_mixer_interface *mixer,
        mutex_init(&private->usb_mutex);
        mutex_init(&private->data_mutex);
        INIT_DELAYED_WORK(&private->work, scarlett2_config_save_work);
+
+       mixer->private_data = private;
+       mixer->private_free = scarlett2_private_free;
+       mixer->private_suspend = scarlett2_private_suspend;
+
        private->info = info;
        scarlett2_count_mux_io(private);
        private->scarlett2_seq = 0;
        private->mixer = mixer;
-       mixer->private_data = private;
-       mixer->private_free = scarlett2_private_free;
-       mixer->private_suspend = scarlett2_private_suspend;
+
+       err = scarlett2_find_fc_interface(mixer->chip->dev, private);
+       if (err < 0)
+               return err;
 
        /* Initialise the sequence number used for the proprietary commands */
        return scarlett2_usb(mixer, SCARLETT2_USB_INIT_SEQ, NULL, 0, NULL, 0);
@@ -2050,8 +2087,8 @@ requeue:
 static int scarlett2_init_notify(struct usb_mixer_interface *mixer)
 {
        struct usb_device *dev = mixer->chip->dev;
-       unsigned int pipe = usb_rcvintpipe(dev,
-                                          SCARLETT2_USB_INTERRUPT_ENDPOINT);
+       struct scarlett2_data *private = mixer->private_data;
+       unsigned int pipe = usb_rcvintpipe(dev, private->bEndpointAddress);
        void *transfer_buffer;
 
        if (mixer->urb) {
@@ -2067,14 +2104,13 @@ static int scarlett2_init_notify(struct usb_mixer_interface *mixer)
        if (!mixer->urb)
                return -ENOMEM;
 
-       transfer_buffer = kmalloc(SCARLETT2_USB_INTERRUPT_MAX_DATA, GFP_KERNEL);
+       transfer_buffer = kmalloc(private->wMaxPacketSize, GFP_KERNEL);
        if (!transfer_buffer)
                return -ENOMEM;
 
        usb_fill_int_urb(mixer->urb, dev, pipe,
-                        transfer_buffer, SCARLETT2_USB_INTERRUPT_MAX_DATA,
-                        scarlett2_notify, mixer,
-                        SCARLETT2_USB_INTERRUPT_INTERVAL);
+                        transfer_buffer, private->wMaxPacketSize,
+                        scarlett2_notify, mixer, private->bInterval);
 
        return usb_submit_urb(mixer->urb, GFP_KERNEL);
 }
@@ -2084,7 +2120,7 @@ static int snd_scarlett_gen2_controls_create(struct usb_mixer_interface *mixer,
 {
        int err;
 
-       /* Initialise private data and sequence number */
+       /* Initialise private data, sequence number, and get the USB data */
        err = scarlett2_init_private(mixer, info);
        if (err < 0)
                return err;