RE: [PATCH] HID: intel-thc-hid: intel-quickspi: reset touch IC on system resume

[Xu, Even]

Hi, Danny,

Nice to meet you!
Thank you very much for your testing and description detail.

According to current situation you described on Surface Pro 10, there are two issues we need to identify separately:
1. Touch IC was powered off
   According to your description, Touch IC power off can be confirmed. 
   In this case, only reset_tic() call is needed for touch IC recovery.

2. THC was power gated
   THC power gated is another story, generally speaking, if device doesn't go into PM_SUSPEND_MEM, THC shouldn't be power gated. If so, other API calls to recovery THC state maybe unnecessary.
   We need to identify this case.

So can you help do a test: just only add reset_tic(), to check if touch device can recovery during suspend/resume.
Then we can identify if THC was power gated.

Thanks!

Best Regards,
Even Xu

> -----Original Message-----
> From: d3z <d3z.the.dev@xxxxxxxxx>
> Sent: Tuesday, June 2, 2026 5:31 AM
> To: Xu, Even <even.xu@xxxxxxxxx>; Sun, Xinpeng <xinpeng.sun@xxxxxxxxx>;
> jikos@xxxxxxxxxx; bentiss@xxxxxxxxxx
> Cc: Danny D . <d3z.the.dev@xxxxxxxxx>; linux-input@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; abhishektamboli9@xxxxxxxxx;
> sakari.ailus@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] HID: intel-thc-hid: intel-quickspi: reset touch IC on system
> resume
> 
> From: Danny D. <d3z.the.dev@xxxxxxxxx>
> 
> Hi Even,
> 
> Thanks for the quick reply and for sharing your patch.
> 
> First, the missing piece from your mail: my name is Danny D.
> (d3z.the.dev@xxxxxxxxx) - please use it for any Signed-off-by/Reported-
> by/Tested-by.
> 
> One note on the starting assumption, though: in its current configuration this
> Surface Pro 10 doesn't go to S3 at all. /sys/power/mem_sleep only offers s2idle:
> 
>     $ cat /sys/power/mem_sleep
>     [s2idle]
> 
> There's no "deep" entry to select here, so every suspend goes through s2idle and
> never reaches PM_SUSPEND_MEM. The touch IC still loses power across that
> s2idle suspend - the same as over hibernation - which is what gives the "recv
> failed: -11" on resume.
> 
> That's the catch with the attached patch: it gates the THC reconfigure on
> 
>     if (last_suspend_state == PM_SUSPEND_MEM)
> 
> i.e. S3 only. On this machine that branch never runs, so it wouldn't bring the
> touchscreen back here. Happy to apply it and confirm on the device, but from the
> code path alone it can't help while we're s2idle-only.
> 
> What I did instead was key off whether the device actually kept power rather
> than the suspend type: run the full reset only when the device isn't a wake source
> (device_may_wakeup() == false), mirroring quickspi_restore().
> A wake-enabled device stays on the light path so wake-on-touch is preserved;
> one that lost power goes through reset_tic() re-enumeration. That fires on both
> s2idle and S3, which is what makes it work on the SP10.
> 
> I've tested this on the Surface Pro 10 across many s2idle suspend/resume cycles -
> touch and pen both keep working - and just posted a v2 that adds the
> device_may_wakeup() gate.
> 
> Could we converge on the wakeup-based condition? I'm glad to test any revision
> of your patch on the hardware, and equally glad for you to carry the fix with my
> Signed-off-by/Tested-by once it handles the s2idle case.
> 
> Thanks,
> Danny