This patch (as863) fixes a problem encountered sometimes when resuming
a port on a UHCI controller. The hardware may turn off the
Resume-Detect bit before turning off the Suspend bit, leading usbcore
to think that the port is still suspended and the resume has failed.
The patch makes uhci_finish_suspend() wait until both bits are safely
off.
Signed-off-by: Alan Stern <[EMAIL PROTECTED]>
---
The same patch will apply to Greg's development tree and to 2.6.20, where
it should go into the stable series. Starting with 2.6.20 we are much
more aggressive about suspending USB devices, so fixing a problem with
resume is important.
Alan Stern
Index: usb-2.6/drivers/usb/host/uhci-hub.c
===================================================================
--- usb-2.6.orig/drivers/usb/host/uhci-hub.c
+++ usb-2.6/drivers/usb/host/uhci-hub.c
@@ -33,6 +33,9 @@ static __u8 root_hub_hub_des[] =
/* status change bits: nonzero writes will clear */
#define RWC_BITS (USBPORTSC_OCC | USBPORTSC_PEC | USBPORTSC_CSC)
+/* suspend/resume bits: port suspended or port resuming */
+#define SUSPEND_BITS (USBPORTSC_SUSP | USBPORTSC_RD)
+
/* A port that either is connected or has a changed-bit set will prevent
* us from AUTO_STOPPING.
*/
@@ -96,8 +99,8 @@ static void uhci_finish_suspend(struct u
int status;
int i;
- if (inw(port_addr) & (USBPORTSC_SUSP | USBPORTSC_RD)) {
- CLR_RH_PORTSTAT(USBPORTSC_SUSP | USBPORTSC_RD);
+ if (inw(port_addr) & SUSPEND_BITS) {
+ CLR_RH_PORTSTAT(SUSPEND_BITS);
if (test_bit(port, &uhci->resuming_ports))
set_bit(port, &uhci->port_c_suspend);
@@ -107,7 +110,7 @@ static void uhci_finish_suspend(struct u
* Experiments show that some controllers take longer, so
* we'll poll for completion. */
for (i = 0; i < 10; ++i) {
- if (!(inw(port_addr) & USBPORTSC_RD))
+ if (!(inw(port_addr) & SUSPEND_BITS))
break;
udelay(1);
}
@@ -289,7 +292,7 @@ static int uhci_hub_control(struct usb_h
wPortStatus |= USB_PORT_STAT_CONNECTION;
if (status & USBPORTSC_PE) {
wPortStatus |= USB_PORT_STAT_ENABLE;
- if (status & (USBPORTSC_SUSP | USBPORTSC_RD))
+ if (status & SUSPEND_BITS)
wPortStatus |= USB_PORT_STAT_SUSPEND;
}
if (status & USBPORTSC_OC)
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