Before a driver is probed, we want to disable USB 3.0 Link Power
Management (LPM), in case the driver needs hub-initiated LPM disabled.
After the probe finishes, we want to attempt to re-enable LPM, order to
balance the LPM ref count.
When a probe fails (such as when libusual doesn't want to bind to a USB
3.0 mass storage device), make sure to balance the LPM ref counts by
re-enabling LPM.
This patch should be backported to kernels as old as 3.5, that contain
the commit 8306095fd2c1100e8244c09bf560f97aca5a311d "USB: Disable USB
3.0 LPM in critical sections."
Signed-off-by: Sarah Sharp <sarah.a.sh...@linux.intel.com>
Cc: sta...@vger.kernel.org
---
drivers/usb/core/driver.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index ddd820d..6056db7 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -367,6 +367,10 @@ static int usb_probe_interface(struct device *dev)
intf->condition = USB_INTERFACE_UNBOUND;
usb_cancel_queued_reset(intf);
+ /* If the LPM disable succeeded, balance the ref counts. */
+ if (!lpm_disable_error)
+ usb_unlocked_enable_lpm(udev);
+
/* Unbound interfaces are always runtime-PM-disabled and -suspended */
if (driver->supports_autosuspend)
pm_runtime_disable(dev);
--
1.7.9
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