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authorAlan Stern <stern@rowland.harvard.edu>2008-07-21 09:56:26 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2008-08-13 17:32:49 -0700
commit38b375d9610e2467cb793a84d17c6f65e44cdb39 (patch)
treebaade98427207a0086b018b153947ae2da7a5802 /drivers/usb/host/ohci-hub.c
parentfa41019c7aa172fde075849834409d23eb49f582 (diff)
USB: OHCI: fix system hang caused by earlier patch
This patch (as1114) fixes a problem that was revealed by an earlier patch (as1069b). Some broken controllers seem never to turn off their RHCS interrupt status bit, even when told to do so. As a result they generate an interrupt storm and hang the system. The patch avoids enabling RHSC interrupt requests when the RHCS status bit is already set. This should have no adverse affects on normal controllers, since they won't set the status bit until a root-hub status change actually occurs, in which case we wouldn't enable RHSC interrupt requests anyway -- we would wait until the status change had been processed and cleared. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested by: Andrey Borzenkov <arvidjaar@mail.ru> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host/ohci-hub.c')
-rw-r--r--drivers/usb/host/ohci-hub.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c
index b56739221d1..d54183f1d70 100644
--- a/drivers/usb/host/ohci-hub.c
+++ b/drivers/usb/host/ohci-hub.c
@@ -483,6 +483,13 @@ ohci_hub_status_data (struct usb_hcd *hcd, char *buf)
length++;
}
+ /* Some broken controllers never turn off RHCS in the interrupt
+ * status register. For their sake we won't re-enable RHSC
+ * interrupts if the flag is already set.
+ */
+ if (ohci_readl(ohci, &ohci->regs->intrstatus) & OHCI_INTR_RHSC)
+ changed = 1;
+
/* look at each port */
for (i = 0; i < ohci->num_ports; i++) {
u32 status = roothub_portstatus (ohci, i);