To do so, create the below registry key and store it in the Default User NTUSER.DAT: Once the user changes the setting, their preference always takes precedence regardless of what the initial OEM default was. The change should be applied to the default user and it will get picked up by each new user on the device. The default for the Wake-On-Touch setting is ON for capable systems, but an OEM can add a registry value specifying the default should instead be OFF. Default State for Wake-On-Touch User Setting Posture changes are a clear indication of user input and this also ensures the proper arming/disarming of the touch controller when the device enters a new posture. Lastly, if it is desired for a device to have different Wake-on-Touch behaviors based on posture, it is recommended to wake the device when a posture change happens. For more information about power transitions, including for HIDUSB and HIDSPI, please see Touchscreen Power Management. This vendor specific mechanism allows the touch controller to disambiguate whether to be scanning for user input or not in the SLEEP/Armed for wake state per the figure below. If the device design does not permit ACPI to pull power (D3 Cold) from the touch controller when Wake-on-Touch is not desired based on posture then a vendor-specific mechanism should be implemented to allow the touch controller to remain powered (D3 Hot) while informing it to go to its lowest power state, internally gating, and not scanning for any touches. In this type of implementation, the filter driver would decide whether to let the IRP flow to ACPI to put the device to D2 (armed for wake) or whether to have the device be put to D3 Cold (off). If it is desired for Wake-on-Touch to only be enabled in certain postures, the recommendation is to implement a filter driver that controls whether the touch controller is armed for wake based on the device posture. If your device matches this form factor or if it is desired for Wake-on-Touch to be enabled regardless of device posture, skip the rest of the content in this section and follow the guidance in the rest of this document. a laptop form factor device), the HID stack will automatically disable Wake-on-Touch when the lid is closed. As an example, a convertible device may only want to enable Wake-on-Touch when it is in its “tablet” state and disable it when it is in its “laptop” state in order to conserve battery.Īvailability of Wake-on-Touch, be it whenever the device is in standby or just in specific postures requires different approaches in implementation.įor systems with a lid (e.g. Device Postureĭifferent postures, device types, and power states should all be taken into consideration for maximum optimization of battery life and reliable UX if the feature is to be utilized. This is considered an abnormal case, but may be desirable for touch IHV to account for in order to minimize unnecessary power consumption in standby. If the touch controller has detected a wake gesture and asserts an interrupt to indicate to the host that input report(s) are ready, but the host does not in fact issue the read, the touch controller should revert back to low power state after some vendor defined timeout. The up and down frames can both be sent immediately, however if scantime usage is present it should be incremented between frames.and will not deliver that input to shell or applications The host will only use these 2 frames as indication of user presence to turn on displays, etc. Touch controller is required to send 2 frames representative of a single finger down and up (X, Y, TIP SET, followed by X, Y, TIP CLEAR) regardless of what gesture was used to cause the wake.Once the touch controller has detected a wake based on either the single tap or double tap gesture: Whichever gesture is chosen shall be usable anywhere on the active area of the display to wake the device. When enabling Wake-on-Touch, OEMs can specify the wake gesture to be either a single-tap or a double-tap working with their touch IHV. Pressing a key on the keyboard, interacting with the touchpad, or clicking the Bluetooth button on a paired pen, are all methods to wake the device with lower power consumption. It is imperative that OEMs consider whether to implement Wake-on-Touch for each design and SKU as there are noticeable power consumption trade-offs for the feature. This document describes how HID based touch devices compatible with Windows can support Wake-On-Touch and what OEMs/ODMs and touch IHVs need to do depending on whether they are using an inbox HID mini-port driver available for USB, I2C or SPI or a 3P HID mini-port specifically for a bus which lacks an inbox driver (i.e. If this functionality is not supported on a device, the setting will not appear on this page.
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