| From stable-bounces@linux.kernel.org Wed Nov 28 14:52:46 2007 |
| From: David Brownell <david-b@pacbell.net> |
| Date: Wed, 28 Nov 2007 14:50:03 -0800 |
| Subject: USB: fix up EHCI startup synchronization |
| To: linux-usb@vger.kernel.org |
| Cc: David Brownell <dbrownell@users.sourceforge.net>, Greg Kroah-Hartman <gregkh@suse.de>, stable <stable@kernel.org>, David Brownell <david-b@pacbell.net>, Alan Stern <stern@rowland.harvard.edu>, Dely Sy <dely.l.sy@intel.com>, Dave Miller <davem@davemloft.net> |
| Message-ID: <1196290207-28564-21-git-send-email-gregkh@suse.de> |
| |
| |
| From: David Brownell <david-b@pacbell.net> |
| |
| patch 1cb52658b4f5b10a9e91f8e1c21ca2bcc1b9a3ca in mainline. |
| |
| A recent patch added software synchronization during EHCI startup, |
| so ports aren't switched away from the companion controllers after |
| resets have started. This patch adds a short delay letting hardware |
| finish that port switching before any new resets begin ... so both |
| ends of that hardware race window are closed. |
| |
| Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> |
| Cc: Dave Miller <davem@davemloft.net> |
| Cc: Dely Sy <dely.l.sy@intel.com> |
| Cc: Alan Stern <stern@rowland.harvard.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| drivers/usb/host/ehci-hcd.c | 5 ++++- |
| 1 file changed, 4 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/usb/host/ehci-hcd.c |
| +++ b/drivers/usb/host/ehci-hcd.c |
| @@ -575,12 +575,15 @@ static int ehci_run (struct usb_hcd *hcd |
| * 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. |
| + * guarantees that no resets are in progress. After we set CF, |
| + * a short delay lets the hardware catch up; new resets shouldn't |
| + * be started before the port switching actions could complete. |
| */ |
| 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 */ |
| + msleep(5); |
| up_write(&ehci_cf_port_reset_rwsem); |
| |
| temp = HC_VERSION(ehci_readl(ehci, &ehci->caps->hc_capbase)); |
