usb: gadget: uvc: Pick up custom string descriptor IDs

If any custom string descriptors have been linked to from the
extension unit, pick up the string ID that was returned when
the strings were attached to the composite dev and use it to
set the iExtension field of the Extension Unit Descriptor.

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230206161802.892954-10-dan.scally@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index f6fd5decdcb7a61ba39353fe57ca287c5a617541..7588ab21f95297a133ad36ab179652ab56f5576d 100644 (file)
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -644,6 +644,7 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 {
        struct usb_composite_dev *cdev = c->cdev;
        struct uvc_device *uvc = to_uvc(f);
+       struct uvcg_extension *xu;
        struct usb_string *us;
        unsigned int max_packet_mult;
        unsigned int max_packet_size;
@@ -736,6 +737,14 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
        uvc_hs_streaming_ep.bEndpointAddress = uvc->video.ep->address;
        uvc_ss_streaming_ep.bEndpointAddress = uvc->video.ep->address;
 
+       /*
+        * XUs can have an arbitrary string descriptor describing them. If they
+        * have one pick up the ID.
+        */
+       list_for_each_entry(xu, &opts->extension_units, list)
+               if (xu->string_descriptor_index)
+                       xu->desc.iExtension = cdev->usb_strings[xu->string_descriptor_index].id;
+
        uvc_en_us_strings[UVC_STRING_CONTROL_IDX].s = opts->function_name;
        us = usb_gstrings_attach(cdev, uvc_function_strings,
                                 ARRAY_SIZE(uvc_en_us_strings));