3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit c183813fcee44a249339b7c46e1ad271ca1870aa upstream.
usb_driver_claim_interface() disables and re-enables Link Power Management, but it shouldn't do either one, for the reasons listed below. This patch removes the two LPM-related function calls from the routine.
The reason for disabling LPM in the analogous function usb_probe_interface() is so that drivers won't have to deal with unwanted LPM transitions in their probe routine. But usb_driver_claim_interface() doesn't call the driver's probe routine (or any other callbacks), so that reason doesn't apply here.
Furthermore, no driver other than usbfs will ever call usb_driver_claim_interface() unless it is already bound to another interface in the same device, which means disabling LPM here would be redundant. usbfs doesn't interact with LPM at all.
Lastly, the error return from usb_unlocked_disable_lpm() isn't handled properly; the code doesn't clean up its earlier actions before returning.
Signed-off-by: Alan Stern stern@rowland.harvard.edu Fixes: 8306095fd2c1 ("USB: Disable USB 3.0 LPM in critical sections.") Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/core/driver.c | 15 --------------- 1 file changed, 15 deletions(-)
--- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -522,7 +522,6 @@ int usb_driver_claim_interface(struct us struct device *dev; struct usb_device *udev; int retval = 0; - int lpm_disable_error = -ENODEV;
if (!iface) return -ENODEV; @@ -539,16 +538,6 @@ int usb_driver_claim_interface(struct us
iface->condition = USB_INTERFACE_BOUND;
- /* See the comment about disabling LPM in usb_probe_interface(). */ - if (driver->disable_hub_initiated_lpm) { - lpm_disable_error = usb_unlocked_disable_lpm(udev); - if (lpm_disable_error) { - dev_err(&iface->dev, "%s Failed to disable LPM for driver %s\n.", - __func__, driver->name); - return -ENOMEM; - } - } - /* Claimed interfaces are initially inactive (suspended) and * runtime-PM-enabled, but only if the driver has autosuspend * support. Otherwise they are marked active, to prevent the @@ -567,10 +556,6 @@ int usb_driver_claim_interface(struct us if (device_is_registered(dev)) retval = device_bind_driver(dev);
- /* Attempt to re-enable USB3 LPM, if the disable was successful. */ - if (!lpm_disable_error) - usb_unlocked_enable_lpm(udev); - return retval; } EXPORT_SYMBOL_GPL(usb_driver_claim_interface);