diff options
Diffstat (limited to 'drivers/usb/host/ehci-hcd.c')
| -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 db00492588b6..c1514442883e 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, |