usb: kbd: On a "usb reset" call usb_kbd_deregister() before calling usb_stop()

We need to call usb_kbd_deregister() before calling usb_stop().

usbkbd's stdio_dev->priv points to the usb_device, and usb_kbd_testc
dereferences usb_device->privptr.

usb_stop zeros usb_device, leaving usb_device->privptr NULL, causing
bad things (tm) to happen once control returns to the main loop and
usb_kbd_testc gets called.

Calling usb_kbd_deregister() avoids this. Note that we do not allow
the "usb reset" to continue when the deregister fails. This will be fixed
in a later patch.

For the same reasons always fail "usb stop" if the usb_kbd_deregister() fails,
even in the force path. This can happen when CONFIG_SYS_STDIO_DEREGISTER is
not set.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

common/cmd_usb.c

@@ -430,6 +430,16 @@ static int do_usbboot(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 }
 #endif /* CONFIG_USB_STORAGE */
 
+static int do_usb_stop_keyboard(void)
+{
+#ifdef CONFIG_USB_KEYBOARD
+	if (usb_kbd_deregister() != 0) {
+		printf("USB not stopped: usbkbd still using USB\n");
+		return 1;
+	}
+#endif
+	return 0;
+}
 
 /******************************************************************************
  * usb command intepreter
@@ -450,6 +460,8 @@ static int do_usb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	if ((strncmp(argv[1], "reset", 5) == 0) ||
 		 (strncmp(argv[1], "start", 5) == 0)) {
 		bootstage_mark_name(BOOTSTAGE_ID_USB_START, "usb_start");
+		if (do_usb_stop_keyboard() != 0)
+			return 1;
 		usb_stop();
 		printf("(Re)start USB...\n");
 		if (usb_init() >= 0) {
@@ -468,19 +480,10 @@ static int do_usb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 		return 0;
 	}
 	if (strncmp(argv[1], "stop", 4) == 0) {
-#ifdef CONFIG_USB_KEYBOARD
-		if (argc == 2) {
-			if (usb_kbd_deregister() != 0) {
-				printf("USB not stopped: usbkbd still"
-					" using USB\n");
-				return 1;
-			}
-		} else {
-			/* forced stop, switch console in to serial */
+		if (argc != 2)
 			console_assign(stdin, "serial");
-			usb_kbd_deregister();
-		}
-#endif
+		if (do_usb_stop_keyboard() != 0)
+			return 1;
 		printf("stopping USB..\n");
 		usb_stop();
 		return 0;