usb: gadget: always update HS/SS descriptors and create a copy of them

HS and SS descriptors are staticaly created. They are updated during the
bind process with the endpoint address, string id or interface numbers.

After that, the descriptor chain is linked to struct usb_function which
is used by composite in order to serve the GET_DESCRIPTOR requests,
number of available configs and so on.

There is no need to assign the HS descriptor only if the UDC supports
HS speed because composite won't report those to the host if HS support
has not been reached. The same reasoning is valid for SS.

This patch makes sure each function updates HS/SS descriptors
unconditionally and uses the newly introduced helper function to create a
copy the descriptors for the speed which is supported by the UDC.

While at that, also rename f->descriptors to f->fs_descriptors in order
to make it more explicit what that means.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/f_serial.c

@@ -213,34 +213,20 @@ gser_bind(struct usb_configuration *c, struct usb_function *f)
 	gser->port.out = ep;
 	ep->driver_data = cdev;	/* claim */
 
-	/* copy descriptors, and track endpoint copies */
-	f->descriptors = usb_copy_descriptors(gser_fs_function);
-
 	/* support all relevant hardware speeds... we expect that when
 	 * hardware is dual speed, all bulk-capable endpoints work at
 	 * both speeds
 	 */
-	if (gadget_is_dualspeed(c->cdev->gadget)) {
-		gser_hs_in_desc.bEndpointAddress =
-				gser_fs_in_desc.bEndpointAddress;
-		gser_hs_out_desc.bEndpointAddress =
-				gser_fs_out_desc.bEndpointAddress;
+	gser_hs_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
+	gser_hs_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;
 
-		/* copy descriptors, and track endpoint copies */
-		f->hs_descriptors = usb_copy_descriptors(gser_hs_function);
-	}
-	if (gadget_is_superspeed(c->cdev->gadget)) {
-		gser_ss_in_desc.bEndpointAddress =
-			gser_fs_in_desc.bEndpointAddress;
-		gser_ss_out_desc.bEndpointAddress =
-			gser_fs_out_desc.bEndpointAddress;
-
-		/* copy descriptors, and track endpoint copies */
-		f->ss_descriptors = usb_copy_descriptors(gser_ss_function);
-		if (!f->ss_descriptors)
-			goto fail;
-	}
+	gser_ss_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
+	gser_ss_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;
 
+	status = usb_assign_descriptors(f, gser_fs_function, gser_hs_function,
+			gser_ss_function);
+	if (status)
+		goto fail;
 	DBG(cdev, "generic ttyGS%d: %s speed IN/%s OUT/%s\n",
 			gser->port_num,
 			gadget_is_superspeed(c->cdev->gadget) ? "super" :
@@ -263,11 +249,7 @@ fail:
 static void
 gser_unbind(struct usb_configuration *c, struct usb_function *f)
 {
-	if (gadget_is_dualspeed(c->cdev->gadget))
-		usb_free_descriptors(f->hs_descriptors);
-	if (gadget_is_superspeed(c->cdev->gadget))
-		usb_free_descriptors(f->ss_descriptors);
-	usb_free_descriptors(f->descriptors);
+	usb_free_all_descriptors(f);
 	kfree(func_to_gser(f));
 }