USB: composite: Add support for functions overriding USB_DT_STRING descriptors

Needed for MTP support.

Signed-off-by: Mike Lockwood <lockwood@android.com>

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 1865b45180ad61ebc9e54372b8ce3c1f0e88471d..d3250ea7f44471de83def2a8203b10a87bcea348 100644 (file)
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -892,6 +892,21 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
                case USB_DT_STRING:
                        value = get_string(cdev, req->buf,
                                        w_index, w_value & 0xff);
+
+                       /* Allow functions to handle USB_DT_STRING.
+                        * This is required for MTP.
+                        */
+                       if (value < 0) {
+                               struct usb_configuration        *cfg;
+                               list_for_each_entry(cfg, &cdev->configs, list) {
+                                       if (cfg && cfg->setup) {
+                                               value = cfg->setup(cfg, ctrl);
+                                               if (value >= 0)
+                                                       break;
+                                       }
+                               }
+                       }
+
                        if (value >= 0)
                                value = min(w_length, (u16) value);
                        break;