Return a valid USB string descriptor for index 0xEE.

Windows will try to retrieve such a descriptor on first connect.
If the device returns STALL or a regular string descriptor (i.e.
not one that follows the Microsoft OS Descriptor spec), things
will continue normally.

Unfortunately some of our low-level USB drivers have issues with
STALL so any other valid descriptor is the next best solution.

Change-Id: I59eb09eea157e4e14bec0197a898be378a5559f2
Reviewed-on: http://gerrit.rockbox.org/680
Reviewed-by: Frank Gevaerts <frank@gevaerts.be>
Tested: Frank Gevaerts <frank@gevaerts.be>

1 files changed, 7 insertions, 0 deletions

diff --git a/firmware/usbstack/usb_core.c b/firmware/usbstack/usb_core.c
index e4ecc90e63..dc69628c13 100644
--- a/firmware/usbstack/usb_core.c
+++ b/firmware/usbstack/usb_core.c
@@ -643,6 +643,13 @@ static void request_handler_device_get_descriptor(struct usb_ctrlrequest* req)
                 size = usb_strings[index]->bLength;
                 ptr = usb_strings[index];
             }
+            else if(index == 0xee) {
+                // We don't have a real OS descriptor, and we don't handle
+                // STALL correctly on some devices, so we return any valid
+                // string (we arbitrarily pick the manufacturer name)
+                size = usb_string_iManufacturer.bLength;
+                ptr = &usb_string_iManufacturer;
+            }
             else {
                 logf("bad string id %d", index);
                 usb_drv_stall(EP_CONTROL, true, true);