| Message ID | 20240129-x13s-touchscreen-v3-2-c4a933034145@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: dts: qcom: sc8280xp-x13s: Enable touchscreen | expand |
On Mon, Jan 29, 2024 at 08:47:48AM -0800, Bjorn Andersson wrote: > The touchscreen present on some SKUs of Lenovo Thinkpad X13s is never > detected by Linux. Power is applied and the device is brought out of > reset using the pinconfig in DeviceTree, but the read-test in > __i2c_hid_core_probe() fails to access the device, which result in probe > being aborted. > > Some users have reported success after rebinding the device. > > Looking to the ACPI tables, there's a 5ms after-power and a 200ms > after-reset delay. The power-supply is shared with other components, so > this is active all the way through boot. The reset GPIO, on the other > hand, is low (reset asserted) at boot, so this is first deasserted by > the implicit application of the pinconf state. > > This means the time between reset deassert and __i2c_hid_core_probe() is > significantly below the value documented in the ACPI tables. > > As the I2C HID binding and driver support specifying a reset gpio, > replace the pinconf-based scheme to pull the device out of reset. Then > specify the after-reset time. > > The shared power rail is currently always on, but in case this ever > change, the after-power delay is added as well, to not violate the > power-on to reset-deassert timing requirement. > > Fixes: 32c231385ed4 ("arm64: dts: qcom: sc8280xp: add Lenovo Thinkpad X13s devicetree") > Tested-by: Daniel Thompson <daniel.thompson@linaro.org> For the sake of completeness (and to make sure I don't forget if anyone asks me in the future) I also (successfully) tested with the output high removed from the touchscreen pinctrl. Daniel. PS Strictly speaking I tested v2 and am replying to v3... but the DT should be the same for both versions ;-).
diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts index def3976bd5bb..33731b95ad51 100644 --- a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts +++ b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts @@ -620,7 +620,6 @@ &i2c4 { status = "okay"; - /* FIXME: verify */ touchscreen@10 { compatible = "hid-over-i2c"; reg = <0x10>; @@ -630,6 +629,11 @@ touchscreen@10 { vdd-supply = <&vreg_misc_3p3>; vddl-supply = <&vreg_s10b>; + reset-gpios = <&tlmm 99 GPIO_ACTIVE_LOW>; + + post-power-on-delay-ms = <5>; + post-reset-deassert-delay-ms = <200>; + pinctrl-names = "default"; pinctrl-0 = <&ts0_default>; }; @@ -1450,7 +1454,6 @@ int-n-pins { reset-n-pins { pins = "gpio99"; function = "gpio"; - output-high; drive-strength = <16>; }; };
The touchscreen present on some SKUs of Lenovo Thinkpad X13s is never detected by Linux. Power is applied and the device is brought out of reset using the pinconfig in DeviceTree, but the read-test in __i2c_hid_core_probe() fails to access the device, which result in probe being aborted. Some users have reported success after rebinding the device. Looking to the ACPI tables, there's a 5ms after-power and a 200ms after-reset delay. The power-supply is shared with other components, so this is active all the way through boot. The reset GPIO, on the other hand, is low (reset asserted) at boot, so this is first deasserted by the implicit application of the pinconf state. This means the time between reset deassert and __i2c_hid_core_probe() is significantly below the value documented in the ACPI tables. As the I2C HID binding and driver support specifying a reset gpio, replace the pinconf-based scheme to pull the device out of reset. Then specify the after-reset time. The shared power rail is currently always on, but in case this ever change, the after-power delay is added as well, to not violate the power-on to reset-deassert timing requirement. Fixes: 32c231385ed4 ("arm64: dts: qcom: sc8280xp: add Lenovo Thinkpad X13s devicetree") Tested-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com> --- arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)