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USB: Defer Set-Interface for suspended devices

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This patch (as1128) fixes one of the problems related to the new PM
infrastructure.  We are not allowed to register new child devices
during the middle of a system sleep transition, but unbinding a USB
driver causes the core to automatically install altsetting 0 and
thereby create new endpoint pseudo-devices.

The patch fixes this problem (and the related problem that installing
altsetting 0 will fail if the device is suspended) by deferring the
Set-Interface call until some later time when it is legal and can
succeed.  Possible later times are: when a new driver is being probed
for the interface, and when the interface is being resumed.

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 2008-08-12 14:33:59 -04:00 committed by Greg Kroah-Hartman
parent 65605ae8e5
commit 55151d7dab
2 changed files with 31 additions and 3 deletions
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31
drivers/usb/core/driver.c
View File

@ -230,6 +230,13 @@ static int usb_probe_interface(struct device *dev)
*/
intf->pm_usage_cnt = !(driver->supports_autosuspend);
/* Carry out a deferred switch to altsetting 0 */
if (intf->needs_altsetting0) {
usb_set_interface(udev, intf->altsetting[0].
desc.bInterfaceNumber, 0);
intf->needs_altsetting0 = 0;
}
error = driver->probe(intf, id);
if (error) {
mark_quiesced(intf);
@ -266,8 +273,17 @@ static int usb_unbind_interface(struct device *dev)
driver->disconnect(intf);
/* reset other interface state */
usb_set_interface(udev, intf->altsetting[0].desc.bInterfaceNumber, 0);
/* Reset other interface state.
* We cannot do a Set-Interface if the device is suspended or
* if it is prepared for a system sleep (since installing a new
* altsetting means creating new endpoint device entries).
* When either of these happens, defer the Set-Interface.
*/
if (!error && intf->dev.power.status == DPM_ON)
usb_set_interface(udev, intf->altsetting[0].
desc.bInterfaceNumber, 0);
else
intf->needs_altsetting0 = 1;
usb_set_intfdata(intf, NULL);
intf->condition = USB_INTERFACE_UNBOUND;
@ -975,8 +991,17 @@ static int usb_resume_interface(struct usb_device *udev,
goto done;
/* Can't resume it if it doesn't have a driver. */
if (intf->condition == USB_INTERFACE_UNBOUND)
if (intf->condition == USB_INTERFACE_UNBOUND) {
/* Carry out a deferred switch to altsetting 0 */
if (intf->needs_altsetting0 &&
intf->dev.power.status == DPM_ON) {
usb_set_interface(udev, intf->altsetting[0].
desc.bInterfaceNumber, 0);
intf->needs_altsetting0 = 0;
}
goto done;
}
/* Don't resume if the interface is marked for rebinding */
if (intf->needs_binding)

3
include/linux/usb.h
View File

@ -110,6 +110,8 @@ enum usb_interface_condition {
* @sysfs_files_created: sysfs attributes exist
* @needs_remote_wakeup: flag set when the driver requires remote-wakeup
* capability during autosuspend.
* @needs_altsetting0: flag set when a set-interface request for altsetting 0
* has been deferred.
* @needs_binding: flag set when the driver should be re-probed or unbound
* following a reset or suspend operation it doesn't support.
* @dev: driver model's view of this device
@ -162,6 +164,7 @@ struct usb_interface {
unsigned is_active:1; /* the interface is not suspended */
unsigned sysfs_files_created:1; /* the sysfs attributes exist */
unsigned needs_remote_wakeup:1; /* driver requires remote wakeup */
unsigned needs_altsetting0:1; /* switch to altsetting 0 is pending */
unsigned needs_binding:1; /* needs delayed unbind/rebind */
struct device dev; /* interface specific device info */