[RFC PATCH 0/7] fix reset line polarity for Goodix touchscreen controllers

[Quentin Schulz]

The Goodix touchscreen controller has a reset line active low. It happens to
also be used to configure its i2c address at runtime. If the reset line is
incorrectly asserted, the address will be wrongly configured. This cost me a few
hours yesterday, trying to figure out why the touchscreen wouldn't work.

The driver is "asserting" this reset GPIO by setting its output to 0, probably
to reflect the physical state of the line. However, this relies on the fact that
the Device Tree node setting the reset line polarity to active high, which is
incorrect since the reset is active low in hardware.

To fix this inconsistency, the polarity is inverted to not confuse the user
about the reset line polarity.

This is marked as RFC because it breaks DT compatibility and also the Google
CoachZ device is the only one with an active low polarity for the reset GPIO
in DT, so not sure if it is a typo or its state is actually inverted (so GPIO
active high to drive the reset line low). Changing it anyways since the polarity
is changed in the driver so it needs to be changed in DT too.

I'm all ears if there's a better way to handle this. We could document this in
the DT binding but this kinda breaks the promise we make that the DT is not
bound to the driver implementation.

Thanks,
Quentin

To: Bastien Nocera <hadess at hadess.net>
To: Hans de Goede <hdegoede at redhat.com>
To: Dmitry Torokhov <dmitry.torokhov at gmail.com>
To: Rob Herring <robh+dt at kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt at linaro.org>
To: Shawn Guo <shawnguo at kernel.org>
To: Sascha Hauer <s.hauer at pengutronix.de>
To: Pengutronix Kernel Team <kernel at pengutronix.de>
To: Fabio Estevam <festevam at gmail.com>
To: NXP Linux Team <linux-imx at nxp.com>
To: Chen-Yu Tsai <wens at csie.org>
To: Jernej Skrabec <jernej.skrabec at gmail.com>
To: Samuel Holland <samuel at sholland.org>
To: Andy Gross <agross at kernel.org>
To: Bjorn Andersson <andersson at kernel.org>
To: Konrad Dybcio <konrad.dybcio at somainline.org>
To: Heiko Stuebner <heiko at sntech.de>
Cc: linux-input at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Cc: devicetree at vger.kernel.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-sunxi at lists.linux.dev
Cc: linux-arm-msm at vger.kernel.org
Cc: linux-rockchip at lists.infradead.org
Signed-off-by: Quentin Schulz <quentin.schulz at theobroma-systems.com>

---
Quentin Schulz (7):
      Input: goodix - fix reset polarity
      ARM: dts: imx: fix touchscreen reset GPIO polarity
      ARM: dts: sunxi: fix touchscreen reset GPIO polarity
      arm64: dts: allwinner: fix touchscreen reset GPIO polarity
      arm64: dts: imx: fix touchscreen reset GPIO polarity
      arm64: dts: qcom: fix touchscreen reset GPIO polarity
      arm64: dts: rockchip: fix touchscreen reset GPIO polarity

 arch/arm/boot/dts/imx6q-kp.dtsi                                  | 2 +-
 arch/arm/boot/dts/imx6ul-kontron-bl-43.dts                       | 2 +-
 arch/arm/boot/dts/sun7i-a20-wexler-tab7200.dts                   | 2 +-
 arch/arm64/boot/dts/allwinner/sun50i-a64-amarula-relic.dts       | 2 +-
 arch/arm64/boot/dts/allwinner/sun50i-a64-oceanic-5205-5inmfd.dts | 2 +-
 arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi          | 2 +-
 arch/arm64/boot/dts/allwinner/sun50i-a64-pinetab.dts             | 2 +-
 arch/arm64/boot/dts/freescale/imx8mm-prt8mm.dts                  | 2 +-
 arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts          | 2 +-
 arch/arm64/boot/dts/qcom/msm8998-fxtec-pro1.dts                  | 2 +-
 arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi              | 2 +-
 arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi            | 2 +-
 arch/arm64/boot/dts/qcom/sc7180-trogdor-mrbland.dtsi             | 2 +-
 arch/arm64/boot/dts/rockchip/px30-evb.dts                        | 2 +-
 arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi               | 2 +-
 arch/arm64/boot/dts/rockchip/rk3568-evb1-v10.dts                 | 2 +-
 drivers/input/touchscreen/goodix.c                               | 4 ++--
 17 files changed, 18 insertions(+), 18 deletions(-)
---
base-commit: 8e5423e991e8cd0988d0c4a3f4ac4ca1af7d148a
change-id: 20221103-upstream-goodix-reset-aa1c65994f57

Best regards,
-- 
Quentin Schulz <quentin.schulz at theobroma-systems.com>