[PATCH v3 09/11] usb: gadget: uvc: Pick up custom string descriptor IDs

[Daniel Scally <dan.scally@ideasonboard.com>]

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>
---
Changes in v3:

	- New patch

 drivers/usb/gadget/function/f_uvc.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index ca548974e5a0..642ab210abb1 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -634,6 +634,7 @@ 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;
@@ -722,6 +723,14 @@ 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));
-- 
2.34.1