[usb] Clear device endpoint halt before resetting host endpoint

Resetting the host endpoint may immediately restart any pending transfers for that endpoint. If the device endpoint halt has not yet been cleared, then this will probably result in a second failed transfer. This second failure may be detected within usb_endpoint_reset() while waiting for usb_clear_feature() to complete. The endpoint will subsequently be removed from the list of halted endpoints, causing the second failure to be effectively ignored and leaving the host endpoint in a permanently halted state. Fix by deferring the host endpoint reset until after the device endpoint is ready to accept new transfers. Signed-off-by: Michael Brown <mcb30@ipxe.org>
ipxe · Jul 2, 2020 · 5d6fb72 · 5d6fb72
1 parent d5874c9
commit 5d6fb72
Showing 1 changed file with 7 additions and 7 deletions.
diff --git a/src/drivers/bus/usb.c b/src/drivers/bus/usb.c
@@ -405,13 +405,6 @@ static int usb_endpoint_reset ( struct usb_endpoint *ep ) {
 	/* Sanity check */
 	assert ( ! list_empty ( &ep->halted ) );
 
-	/* Reset endpoint */
-	if ( ( rc = ep->host->reset ( ep ) ) != 0 ) {
-		DBGC ( usb, "USB %s %s could not reset: %s\n",
-		       usb->name, usb_endpoint_name ( ep ), strerror ( rc ) );
-		return rc;
-	}
-
 	/* Clear transaction translator, if applicable */
 	if ( ( rc = usb_endpoint_clear_tt ( ep ) ) != 0 )
 		return rc;
@@ -427,6 +420,13 @@ static int usb_endpoint_reset ( struct usb_endpoint *ep ) {
 		return rc;
 	}
 
+	/* Reset endpoint */
+	if ( ( rc = ep->host->reset ( ep ) ) != 0 ) {
+		DBGC ( usb, "USB %s %s could not reset: %s\n",
+		       usb->name, usb_endpoint_name ( ep ), strerror ( rc ) );
+		return rc;
+	}
+
 	/* Remove from list of halted endpoints */
 	list_del ( &ep->halted );
 	INIT_LIST_HEAD ( &ep->halted );