[PATCH 5/7] arm64: dts: qcom: c630: Wait for the touchpad at resume

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

When the SoC reaches deep sleep (AOSS sleep and CX collapse) in suspend
to idle, the touchpad is often reset, presumably because it loses power,
and it may still be starting up when it is powered on again at resume.
If it doesn't acknowledge the power on command, i2c-hid tries once more
0.5 ms later, and then fails the resume:

  [  712.566907] i2c_hid_of 3-0015: failed to change power setting.
  [  712.567528] i2c_hid_of 3-0015: PM: dpm_run_callback(): i2c_hid_core_pm_resume [i2c_hid] returns -6

hid-multitouch then never puts the touchpad back into touchpad mode, so
it stays in the mouse mode it starts up in, without two-finger
scrolling, until the next suspend and resume.

This happened after about one in eight suspends. With a debug patch that
keeps trying, the touchpad answered the next attempt, about 6 ms later,
each time it had missed the first two.

So give the touchpad a post power on delay of 20 ms, which i2c-hid-of
waits for at probe, and at every resume before powering the touchpad on,
as the touchpad isn't a wakeup source.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts b/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts
index 3e4df4335be8..accd80005195 100644
--- a/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts
+++ b/arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts
@@ -496,6 +496,8 @@ tsel: hid@15 {
 		hid-descr-addr = <0x1>;
 
 		interrupts-extended = <&tlmm 37 IRQ_TYPE_LEVEL_HIGH>;
+
+		post-power-on-delay-ms = <20>;
 	};
 
 	tsc2: hid@2c {
-- 
2.56.0.611.g1030f0b940-goog