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USB: use reset_resume when normal resume fails

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This patch (as1109b) makes USB-Persist more resilient to errors.  With
the current code, if a normal resume fails, it's an unrecoverable
error.  With the patch, if a normal resume fails (and if the device is
enabled for USB-Persist) then a reset-resume is tried.

This fixes the problem reported in Bugzilla #10977.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern 2008-06-30 11:14:43 -04:00 committed by Greg Kroah-Hartman
parent ac90e36592
commit 86c57edf60
2 changed files with 22 additions and 5 deletions
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7
Documentation/usb/persist.txt
View File

@ -81,8 +81,11 @@ re-enumeration shows that the device now attached to that port has the
same descriptors as before, including the Vendor and Product IDs, then
the kernel continues to use the same device structure. In effect, the
kernel treats the device as though it had merely been reset instead of
unplugged. The same thing happens if the host controller is in the
expected state but a USB device was unplugged and then replugged.
unplugged.
The same thing happens if the host controller is in the expected state
but a USB device was unplugged and then replugged, or if a USB device
fails to carry out a normal resume.
If no device is now attached to the port, or if the descriptors are
different from what the kernel remembers, then the treatment is what

20
drivers/usb/core/hub.c
View File

@ -1822,9 +1822,15 @@ static int check_port_resume_type(struct usb_device *udev,
status = -ENODEV;
}
/* Can't do a normal resume if the port isn't enabled */
else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume)
status = -ENODEV;
/* Can't do a normal resume if the port isn't enabled,
* so try a reset-resume instead.
*/
else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume) {
if (udev->persist_enabled)
udev->reset_resume = 1;
else
status = -ENODEV;
}
if (status) {
dev_dbg(hub->intfdev,
@ -1973,6 +1979,7 @@ static int finish_port_resume(struct usb_device *udev)
* resumed.
*/
if (udev->reset_resume)
retry_reset_resume:
status = usb_reset_and_verify_device(udev);
/* 10.5.4.5 says be sure devices in the tree are still there.
@ -1984,6 +1991,13 @@ static int finish_port_resume(struct usb_device *udev)
status = usb_get_status(udev, USB_RECIP_DEVICE, 0, &devstatus);
if (status >= 0)
status = (status > 0 ? 0 : -ENODEV);
/* If a normal resume failed, try doing a reset-resume */
if (status && !udev->reset_resume && udev->persist_enabled) {
dev_dbg(&udev->dev, "retry with reset-resume\n");
udev->reset_resume = 1;
goto retry_reset_resume;
}
}
if (status) {