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authorDavid Brownell <david-b@pacbell.net>2007-11-13 16:22:30 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2007-11-28 13:58:36 -0800
commit1cb52658b4f5b10a9e91f8e1c21ca2bcc1b9a3ca (patch)
tree9eff6108b82b903783ae66977a475219b03dfb2c /drivers/usb
parent5cf1973a44bd298e3cfce6f6af8faa8c9d0a6d55 (diff)
USB: fix up EHCI startup synchronization
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: stable <stable@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/host/ehci-hcd.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index c1514442883..5f2d74ed5ad 100644
--- 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));