From: Alan Stern Date: Wed, 10 Oct 2007 20:27:07 +0000 (-0400) Subject: USB: mutual exclusion for EHCI init and port resets X-Git-Tag: v2.6.24-rc1~1395^2~6 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=32fe01985aa2cb2562f6fc171e526e279abe10db;p=linux-2.6 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 --- diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h index 1396141274..98e24194a4 100644 --- a/drivers/usb/core/hcd.h +++ b/drivers/usb/core/hcd.h @@ -19,6 +19,8 @@ #ifdef __KERNEL__ +#include + /* This file contains declarations of usbcore internals that are mostly * used or exposed by Host Controller Drivers. */ @@ -470,5 +472,9 @@ static inline void usbmon_urb_complete(struct usb_bus *bus, struct urb *urb, : (in_interrupt () ? "in_interrupt" : "can sleep")) -#endif /* __KERNEL__ */ +/* This rwsem is for use only by the hub driver and ehci-hcd. + * Nobody else should touch it. + */ +extern struct rw_semaphore ehci_cf_port_reset_rwsem; +#endif /* __KERNEL__ */ diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 481dca641e..d20cb545a6 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; } diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index db00492588..c151444288 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -570,10 +570,18 @@ static int ehci_run (struct usb_hcd *hcd) * are explicitly handed to companion controller(s), so no TT is * involved with the root hub. (Except where one is integrated, * and there's no companion controller unless maybe for USB OTG.) + * + * Turning on the CF flag will transfer ownership of all ports + * from the companions to the EHCI controller. If any of the + * companions are in the middle of a port reset at the time, it + * could cause trouble. Write-locking ehci_cf_port_reset_rwsem + * guarantees that no resets are in progress. */ + down_write(&ehci_cf_port_reset_rwsem); hcd->state = HC_STATE_RUNNING; ehci_writel(ehci, FLAG_CF, &ehci->regs->configured_flag); ehci_readl(ehci, &ehci->regs->command); /* unblock posted writes */ + up_write(&ehci_cf_port_reset_rwsem); temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase)); ehci_info (ehci,