uas: Add a uas_find_uas_alt_setting helper function

This is a preparation patch for teaching usb-storage to not bind to
uas devices.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 3f021f2fafdf..54db36541b93 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -892,10 +892,10 @@ static int uas_isnt_supported(struct usb_device *udev)
         return -ENODEV;
 }
 
-static int uas_switch_interface(struct usb_device *udev,
-                                                struct usb_interface *intf)
+static int uas_find_uas_alt_setting(struct usb_interface *intf)
 {
         int i;
+        struct usb_device *udev = interface_to_usbdev(intf);
         int sg_supported = udev->bus->sg_tablesize != 0;
 
         for (i = 0; i < intf->num_altsetting; i++) {
@@ -904,15 +904,26 @@ static int uas_switch_interface(struct usb_device *udev,
                 if (uas_is_interface(alt)) {
                         if (!sg_supported)
                                 return uas_isnt_supported(udev);
-                        return usb_set_interface(udev,
-                                                alt->desc.bInterfaceNumber,
-                                                alt->desc.bAlternateSetting);
+                        return alt->desc.bAlternateSetting;
                 }
         }
 
         return -ENODEV;
 }
 
+static int uas_switch_interface(struct usb_device *udev,
+                                struct usb_interface *intf)
+{
+        int alt;
+
+        alt = uas_find_uas_alt_setting(intf);
+        if (alt < 0)
+                return alt;
+
+        return usb_set_interface(udev,
+                        intf->altsetting[0].desc.bInterfaceNumber, alt);
+}
+
 static void uas_configure_endpoints(struct uas_dev_info *devinfo)
 {
         struct usb_host_endpoint *eps[4] = { };