USB: implement usb_enable_autosuspend (088f7fec) · Commits · e / devices / android_kernel_fairphone_FP3

Documentation/usb/power-management.txt

+18 −0

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		@@ -229,6 +229,11 @@ necessary operations by hand or add them to a udev script. You can
		also change the idle-delay time; 2 seconds is not the best choice for
		every device.

		If a driver knows that its device has proper suspend/resume support,
		it can enable autosuspend all by itself. For example, the video
		driver for a laptop's webcam might do this, since these devices are
		rarely used and so should normally be autosuspended.

		Sometimes it turns out that even when a device does work okay with
		autosuspend there are still problems. For example, there are
		experimental patches adding autosuspend support to the usbhid driver,
		@@ -384,6 +389,19 @@ autosuspend, there's no delay for an autoresume.
		Other parts of the driver interface
		-----------------------------------

		Drivers can enable autosuspend for their devices by calling

		usb_enable_autosuspend(struct usb_device *udev);

		in their probe() routine, if they know that the device is capable of
		suspending and resuming correctly. This is exactly equivalent to
		writing "auto" to the device's power/level attribute. Likewise,
		drivers can disable autosuspend by calling

		usb_disable_autosuspend(struct usb_device *udev);

		This is exactly the same as writing "on" to the power/level attribute.

		Sometimes a driver needs to make sure that remote wakeup is enabled
		during autosuspend. For example, there's not much point
		autosuspending a keyboard if the user can't cause the keyboard to do a

+42 −0

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		@@ -1415,6 +1415,48 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)

		#ifdef CONFIG_USB_SUSPEND

		/**
		* usb_enable_autosuspend - allow a USB device to be autosuspended
		* @udev: the USB device which may be autosuspended
		*
		* This routine allows @udev to be autosuspended. An autosuspend won't
		* take place until the autosuspend_delay has elapsed and all the other
		* necessary conditions are satisfied.
		*
		* The caller must hold @udev's device lock.
		*/
		int usb_enable_autosuspend(struct usb_device *udev)
		{
		if (udev->autosuspend_disabled) {
		udev->autosuspend_disabled = 0;
		usb_autosuspend_device(udev);
		}
		return 0;
		}
		EXPORT_SYMBOL_GPL(usb_enable_autosuspend);

		/**
		* usb_disable_autosuspend - prevent a USB device from being autosuspended
		* @udev: the USB device which may not be autosuspended
		*
		* This routine prevents @udev from being autosuspended and wakes it up
		* if it is already autosuspended.
		*
		* The caller must hold @udev's device lock.
		*/
		int usb_disable_autosuspend(struct usb_device *udev)
		{
		int rc = 0;

		if (!udev->autosuspend_disabled) {
		rc = usb_autoresume_device(udev);
		if (rc == 0)
		udev->autosuspend_disabled = 1;
		}
		return rc;
		}
		EXPORT_SYMBOL_GPL(usb_disable_autosuspend);

		/* Internal routine to adjust a device's usage counter and change
		* its autosuspend state.
		*/

+3 −0

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		@@ -1224,6 +1224,9 @@ static int hub_probe(struct usb_interface intf, const struct usb_device_id id)
		desc = intf->cur_altsetting;
		hdev = interface_to_usbdev(intf);

		/* Hubs have proper suspend/resume support */
		usb_enable_autosuspend(hdev);

		if (hdev->level == MAX_TOPO_LEVEL) {
		dev_err(&intf->dev,
		"Unsupported bus topology: hub nested too deep\n");

+4 −5

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		@@ -103,11 +103,10 @@ void usb_detect_quirks(struct usb_device *udev)
		dev_dbg(&udev->dev, "USB quirks for this device: %x\n",
		udev->quirks);

		/* By default, disable autosuspend for all non-hubs */
		#ifdef CONFIG_USB_SUSPEND
		if (udev->descriptor.bDeviceClass != USB_CLASS_HUB)
		udev->autosuspend_disabled = 1;
		#endif
		/* By default, disable autosuspend for all devices. The hub driver
		* will enable it for hubs.
		*/
		usb_disable_autosuspend(udev);

		/* For the present, all devices default to USB-PERSIST enabled */
		#if 0 /* was: #ifdef CONFIG_PM */

+7 −16

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		@@ -389,34 +389,25 @@ set_level(struct device dev, struct device_attribute attr,
		struct usb_device *udev = to_usb_device(dev);
		int len = count;
		char *cp;
		int rc = 0;
		int old_autosuspend_disabled;
		int rc;

		cp = memchr(buf, '\n', count);
		if (cp)
		len = cp - buf;

		usb_lock_device(udev);
		old_autosuspend_disabled = udev->autosuspend_disabled;

		/* Setting the flags without calling usb_pm_lock is a subject to
		* races, but who cares...
		*/
		if (len == sizeof on_string - 1 &&
		strncmp(buf, on_string, len) == 0) {
		udev->autosuspend_disabled = 1;
		rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
		strncmp(buf, on_string, len) == 0)
		rc = usb_disable_autosuspend(udev);

		} else if (len == sizeof auto_string - 1 &&
		strncmp(buf, auto_string, len) == 0) {
		udev->autosuspend_disabled = 0;
		rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
		else if (len == sizeof auto_string - 1 &&
		strncmp(buf, auto_string, len) == 0)
		rc = usb_enable_autosuspend(udev);

		} else
		else
		rc = -EINVAL;

		if (rc)
		udev->autosuspend_disabled = old_autosuspend_disabled;
		usb_unlock_device(udev);
		return (rc < 0 ? rc : count);
		}