[PATCH v2 9/9] usb: gadget: uvc: Use custom strings if available

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

If the user has defined a custom string descriptor for the IAD or the
VideoControl or VideoStreaming interfaces then set their index field
to point to the custom descriptor instead of the hardcoded defaults.
If no custom descriptors have been linked to, then use the default
ones.

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
---
Changes in v2:

	- New patch

 drivers/usb/gadget/function/f_uvc.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index 7821fe8f9120..ac6df8458cab 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -784,6 +784,10 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 	list_for_each_entry(xu, &opts->extension_units, list)
 		xu->desc.iExtension = cus[xu->string_descriptor_index].id;
 
+	/*
+	 * We attach the hard-coded defaults incase the user does not provide
+	 * any more appropriate strings through configfs.
+	 */
 	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));
@@ -791,11 +795,15 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 		ret = PTR_ERR(us);
 		goto error;
 	}
-	uvc_iad.iFunction = us[UVC_STRING_CONTROL_IDX].id;
-	uvc_control_intf.iInterface = us[UVC_STRING_CONTROL_IDX].id;
-	ret = us[UVC_STRING_STREAMING_IDX].id;
-	uvc_streaming_intf_alt0.iInterface = ret;
-	uvc_streaming_intf_alt1.iInterface = ret;
+
+	uvc_iad.iFunction = opts->iad_index ? cus[opts->iad_index].id :
+			    us[UVC_STRING_CONTROL_IDX].id;
+	uvc_control_intf.iInterface = opts->iad_index ? cus[opts->iad_index].id :
+				      us[UVC_STRING_CONTROL_IDX].id;
+	uvc_streaming_intf_alt0.iInterface = opts->vs0_index ? cus[opts->vs0_index].id :
+					     us[UVC_STRING_STREAMING_IDX].id;
+	uvc_streaming_intf_alt1.iInterface = opts->vs1_index ? cus[opts->vs1_index].id :
+					     us[UVC_STRING_STREAMING_IDX].id;
 
 	/* Allocate interface IDs. */
 	if ((ret = usb_interface_id(c, f)) < 0)
-- 
2.34.1