[PATCH] USB: otg hub support is optional
USB OTG devices are not required to support external hubs. This adds a
configuration option to disable that support.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index ff03184..a08787e 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -99,4 +99,11 @@
normal Linux-USB hosts do (other than the warning), and is
convenient for many stages of product development.
+config USB_OTG_BLACKLIST_HUB
+ bool "Disable external hubs"
+ depends on USB_OTG
+ help
+ If you say Y here, then Linux will refuse to enumerate
+ external hubs. OTG hosts are allowed to reduce hardware
+ and software costs by not supporting external hubs.
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 3c76f7e..0c87f73 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -836,6 +836,13 @@
desc = intf->cur_altsetting;
hdev = interface_to_usbdev(intf);
+#ifdef CONFIG_USB_OTG_BLACKLIST_HUB
+ if (hdev->parent) {
+ dev_warn(&intf->dev, "ignoring external hub\n");
+ return -ENODEV;
+ }
+#endif
+
/* Some hubs have a subclass of 1, which AFAICT according to the */
/* specs is not defined, but it works */
if ((desc->desc.bInterfaceSubClass != 0) &&