Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=32fe01985aa2cb2562f6fc171e526e279abe10db
Commit: 32fe01985aa2cb2562f6fc171e526e279abe10db
Parent: 17f060224fb9f435c6f9306b7b61419d038def13
Author: Alan Stern <[EMAIL PROTECTED]>
AuthorDate: Wed Oct 10 16:27:07 2007 -0400
Committer: Greg Kroah-Hartman <[EMAIL PROTECTED]>
CommitDate: Fri Oct 12 14:55:34 2007 -0700
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 <[EMAIL PROTECTED]>
Acked-by: David Brownell <[EMAIL PROTECTED]>
Cc: David Miller <[EMAIL PROTECTED]>
Cc: Dely L Sy <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
---
drivers/usb/core/hcd.h | 8 +++++++-
drivers/usb/core/hub.c | 15 ++++++++++++++-
drivers/usb/host/ehci-hcd.c | 8 ++++++++
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index 1396141..98e2419 100644
--- a/drivers/usb/core/hcd.h
+++ b/drivers/usb/core/hcd.h
@@ -19,6 +19,8 @@
#ifdef __KERNEL__
+#include <linux/rwsem.h>
+
/* 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 481dca6..d20cb54 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 db00492..c151444 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,
-
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