| Message ID | 20240507144821.12275-1-johan+linaro@kernel.org |
|---|---|
| Headers | show |
| Series | HID/arm64: dts: qcom: sc8280xp-x13s: fix touchscreen power on | expand |
On Tue, 07 May 2024 16:48:14 +0200, Johan Hovold wrote: > The Elan eKTH5015M touch controller on the X13s requires a 300 ms delay > before sending commands after having deasserted reset during power on. > > This series switches the X13s devicetree to use the Elan specific > binding so that the OS can determine the required power-on sequence and > make sure that the controller is always detected during boot. [1] > > [...] Applied, thanks! [7/7] arm64: defconfig: enable Elan i2c-hid driver commit: e706474d8428f420bba11f2c49c3083fd1b31d88 Best regards,
The Elan eKTH5015M touch controller on the X13s requires a 300 ms delay before sending commands after having deasserted reset during power on. This series switches the X13s devicetree to use the Elan specific binding so that the OS can determine the required power-on sequence and make sure that the controller is always detected during boot. [1] The Elan hid-i2c driver currently asserts reset unconditionally during suspend, which does not work on the X13s where the touch controller supply is shared with other peripherals that may remain powered. Holding the controller in reset can increase power consumption and also leaks current through the reset circuitry pull ups. Note that the latter also affects X13s variants where the touchscreen is not populated as the driver also exits probe() with reset asserted. Fix this by adding a new 'no-reset-on-power-off' devicetree property which can be used by the OS to determine when reset needs to be asserted on power down and when it safe and desirable to leave it deasserted. I tried to look for drivers that had already addressed this but it was only after I finished implementing this that I noticed Doug's reference to commit 18eeef46d359 ("HID: i2c-hid: goodix: Tie the reset line to true state of the regulator"), which tried to solve a related problem. That commit has since been reverted but ultimately resulted in commit 7607f12ba735 ("HID: i2c-hid: goodix: Add support for "goodix,no-reset-during-suspend" property") being merged to handle the related case where the touch controller supply is always on. The implementation is very similar, but I decided to use the slightly more generic 'no-reset-on-power-off' property name after considering a number of alternatives (including trying to describe the hardware configuration in the name). (And as this is not vendor specific, I left out the prefix.) Note that my X13s does not have a touchscreen, but I have done partial verification of the implementation using that machine and the sc8280xp CRD reference design. Bjorn has promised to help out with final verification on an X13s with a touchscreen. The devicetree changes are expected to go in through the Qualcomm tree once the binding and driver updates have been merged. Johan [1] The reset signal is currently deasserted using the pin configuration and the controller would be detected if probe is deferred or if user space triggers a reprobe through sysfs. Changes in v2 - drop redundant 'items' from binding - include a "should" in description of 'no-reset-on-power-off' property - always assert reset on probe - enable elan i2c-hid driver in arm64 defconfig Johan Hovold (7): dt-bindings: HID: i2c-hid: add dedicated Ilitek ILI2901 schema dt-bindings: HID: i2c-hid: elan: add Elan eKTH5015M dt-bindings: HID: i2c-hid: elan: add 'no-reset-on-power-off' property HID: i2c-hid: elan: fix reset suspend current leakage arm64: dts: qcom: sc8280xp-x13s: fix touchscreen power on arm64: dts: qcom: sc8280xp-crd: use external pull up for touch reset arm64: defconfig: enable Elan i2c-hid driver .../bindings/input/elan,ekth6915.yaml | 19 ++++-- .../bindings/input/ilitek,ili2901.yaml | 66 +++++++++++++++++++ arch/arm64/boot/dts/qcom/sc8280xp-crd.dts | 3 +- .../qcom/sc8280xp-lenovo-thinkpad-x13s.dts | 15 +++-- arch/arm64/configs/defconfig | 1 + drivers/hid/i2c-hid/i2c-hid-of-elan.c | 59 +++++++++++++---- 6 files changed, 137 insertions(+), 26 deletions(-) create mode 100644 Documentation/devicetree/bindings/input/ilitek,ili2901.yaml