Re: [PATCH RFC] mfd: intel-lpss: Set d3hot_delay to 0

[Navon John Lukose <navonjohnlukose@gmail.com>]

On Fri, Oct 16, 2026 at 04:16:20PM +0300, Andy Shevchenko wrote:
> So, do you state that this patch fixes some bad touchpad behaviour? If so,
> please, provide some logs.

No, nothing misbehaves without it, so this is only an optimisation. It
shortens the first touchpad report after the controller has autosuspended.
I went after it because the driver already clears d3cold_delay and the
D3hot one looked like it had been missed.

I timed the i2c-hid threaded IRQ handler for the touchpad (CIRQ1080 behind
00:15.0) with bpftrace, switching d3hot_delay at runtime:

                                   d3hot_delay=10   d3hot_delay=0
  controller already awake         ~1.1 ms          ~1.1 ms
  controller resumed in handler    12.6-14.4 ms     1.1-1.9 ms

There were no I2C errors with either value. That is about 12 ms saved once
per idle period, which is not much. If nobody can vouch for the older
generations, limiting it to newer IDs or dropping it is fine with me.