From 32fe01985aa2cb2562f6fc171e526e279abe10db Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Wed, 10 Oct 2007 16:27:07 -0400 Subject: USB: mutual exclusion for EHCI init and port resets This patch (as999) fixes a problem that sometimes shows up when host controller driver modules are loaded in the wrong order. If ehci-hcd happens to initialize an EHCI controller while the companion OHCI or UHCI controller is in the middle of a port reset, the reset can fail and the companion may get very confused. The patch adds an rw-semaphore and uses it to keep EHCI initialization and port resets mutually exclusive. Signed-off-by: Alan Stern Acked-by: David Brownell Cc: David Miller Cc: Dely L Sy Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'drivers/usb/core/hub.c') diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 481dca641ea2..d20cb545a6e4 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -125,6 +125,12 @@ MODULE_PARM_DESC(use_both_schemes, "try the other device initialization scheme if the " "first one fails"); +/* Mutual exclusion for EHCI CF initialization. This interferes with + * port reset on some companion controllers. + */ +DECLARE_RWSEM(ehci_cf_port_reset_rwsem); +EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem); + static inline char *portspeed(int portstatus) { @@ -1581,6 +1587,11 @@ static int hub_port_reset(struct usb_hub *hub, int port1, { int i, status; + /* Block EHCI CF initialization during the port reset. + * Some companion controllers don't like it when they mix. + */ + down_read(&ehci_cf_port_reset_rwsem); + /* Reset the port */ for (i = 0; i < PORT_RESET_TRIES; i++) { status = set_port_feature(hub->hdev, @@ -1612,7 +1623,7 @@ static int hub_port_reset(struct usb_hub *hub, int port1, usb_set_device_state(udev, status ? USB_STATE_NOTATTACHED : USB_STATE_DEFAULT); - return status; + goto done; } dev_dbg (hub->intfdev, @@ -1625,6 +1636,8 @@ static int hub_port_reset(struct usb_hub *hub, int port1, "Cannot enable port %i. Maybe the USB cable is bad?\n", port1); + done: + up_read(&ehci_cf_port_reset_rwsem); return status; } -- cgit v1.2.3-55-g7522