diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2007-10-10 16:27:07 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-10-12 14:55:34 -0700 |
| commit | 32fe01985aa2cb2562f6fc171e526e279abe10db (patch) | |
| tree | 0c1865a1d3e91ae0839147430480c4099b16a06f /drivers/usb/host | |
| parent | 17f060224fb9f435c6f9306b7b61419d038def13 (diff) | |
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 <stern@rowland.harvard.edu>
Acked-by: David Brownell <david-b@pacbell.net>
Cc: David Miller <davem@davemloft.net>
Cc: Dely L Sy <dely.l.sy@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host')
| -rw-r--r-- | drivers/usb/host/ehci-hcd.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index db00492588b..c1514442883 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, |