USB: Fix LPM disable/enable during device reset. (6d1d0513) · Commits · 戴 / test

The USB 3.0 specification says that sending a Set Feature or Clear Feature for U1/U2 Enable is not a valid request when the device is in the Default or Addressed state. It is only valid when the device is in the Configured state. The original LPM patch attempted to disable LPM after the device had been reset by hub_port_init(), before it had the configuration reinstalled. The TI hub I tested with did not fail the Clear Feature U1/U2 Enable request that khubd sent while it was in the addressed state, which is why I didn't catch it. Move the LPM disable before the device reset, so that we can send the Clear Feature U1/U2 Enable successfully, and balance the LPM disable count. Also delete any calls to usb_enable_lpm() on error paths that lead to re-enumeration. The calls will fail because the device isn't configured, and it's not useful to balance the LPM disable count because the usb_device is about to be destroyed before re-enumeration. Fix the early exit path ("done" label) to call usb_enable_lpm() to balance the LPM disable count. Note that calling usb_reset_and_verify_device() with an unconfigured device may fail on the first call to usb_disable_lpm(). That's because the LPM disable count is initialized to 0 (LPM enabled), and usb_disable_lpm() will attempt to send a Clear Feature U1/U2 request to a device in the Addressed state. The next patch will fix that. This commit should be backported to kernels as old as 3.5, that contain the commit "USB: Disable USB 3.0 LPM in critical sections." Signed-off-by:

Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: stable@vger.kernel.org

drivers/usb/core/hub.c

+12 −14

Original line number	Diff line number	Diff line
		@@ -4673,6 +4673,16 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
		}
		parent_hub = hdev_to_hub(parent_hdev);

		/* Disable LPM while we reset the device and reinstall the alt settings.
		* Device-initiated LPM settings, and system exit latency settings are
		* cleared when the device is reset, so we have to set them up again.
		*/
		ret = usb_unlocked_disable_lpm(udev);
		if (ret) {
		dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__);
		goto re_enumerate;
		}

		set_bit(port1, parent_hub->busy_bits);
		for (i = 0; i < SET_CONFIG_TRIES; ++i) {

		@@ -4700,22 +4710,11 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
		goto done;

		mutex_lock(hcd->bandwidth_mutex);
		/* Disable LPM while we reset the device and reinstall the alt settings.
		* Device-initiated LPM settings, and system exit latency settings are
		* cleared when the device is reset, so we have to set them up again.
		*/
		ret = usb_disable_lpm(udev);
		if (ret) {
		dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__);
		mutex_unlock(hcd->bandwidth_mutex);
		goto done;
		}
		ret = usb_hcd_alloc_bandwidth(udev, udev->actconfig, NULL, NULL);
		if (ret < 0) {
		dev_warn(&udev->dev,
		"Busted HC? Not enough HCD resources for "
		"old configuration.\n");
		usb_enable_lpm(udev);
		mutex_unlock(hcd->bandwidth_mutex);
		goto re_enumerate;
		}
		@@ -4727,7 +4726,6 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
		dev_err(&udev->dev,
		"can't restore configuration #%d (error=%d)\n",
		udev->actconfig->desc.bConfigurationValue, ret);
		usb_enable_lpm(udev);
		mutex_unlock(hcd->bandwidth_mutex);
		goto re_enumerate;
		}
		@@ -4766,17 +4764,17 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
		desc->bInterfaceNumber,
		desc->bAlternateSetting,
		ret);
		usb_unlocked_enable_lpm(udev);
		goto re_enumerate;
		}
		}

		done:
		/* Now that the alt settings are re-installed, enable LPM. */
		usb_unlocked_enable_lpm(udev);
		done:
		return 0;

		re_enumerate:
		/* LPM state doesn't matter when we're about to destroy the device. */
		hub_port_logical_disconnect(parent_hub, port1);
		return -ENODEV;
		}

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