From: Alan Stern Date: Mon, 21 Jul 2008 13:56:26 +0000 (-0400) Subject: USB: OHCI: fix system hang caused by earlier patch X-Git-Tag: v2.6.27-rc4~101^2~40 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=38b375d9610e2467cb793a84d17c6f65e44cdb39;p=linux-2.6 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 Tested by: Andrey Borzenkov Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c index b56739221d..d54183f1d7 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);