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SubjectRe: [PATCH] HID: i2c-hid: Disable runtime PM on Goodix touchpad
On Thu, Jan 17, 2019 at 12:41 PM Kai-Heng Feng
<kai.heng.feng@canonical.com> wrote:
>
>
>
> > On Jan 17, 2019, at 16:06, Benjamin Tissoires <benjamin.tissoires@redhat.com> wrote:
> >
> > On Thu, Jan 17, 2019 at 6:02 AM Kai-Heng Feng
> > <kai.heng.feng@canonical.com> wrote:
> [snipped]
> >> Goodix says the firmware needs at least 60ms to fully respond ON and
> >> SLEEP command.
> >
> > I was about to say that this is not conformant to the specification.
> > But looking at 7.2.8 SET_POWER of
> > https://docs.microsoft.com/en-us/previous-versions/windows/hardware/design/dn642101(v=vs.85)
> >
> > They say:
> > "The DEVICE must ensure that it transitions to the HOST specified
> > Power State in under 1 second. "
> > But in the RESPONSE paragraph: "The DEVICE shall not respond back
> > after receiving the command. The DEVICE is mandated to enter that
> > power state imminently."
> >
> > My interpretation was always that the device has to be in a ready
> > state for new commands "immediately".
> > However, the first sentence may suggest that the driver would block
> > any command to the device before the 1 second timestamp.
> >
> >>
> >> I’ll see if an 200ms autosuspend can solve all Goodix, LG and Raydium
> >> touchpanels.
> >
> > We already have a I2C_HID_QUIRK_DELAY_AFTER_SLEEP quirk that delay
> > operations after sleep by 20ms. Maybe we can keep the runtime PM but
> > use the same timers to not confuse the hardware.
>
> Yes, but wouldn’t use pm_*_autosuspend() helpers can both solve the issue
> and make the code more cleaner?

You are probably correct :)

I am not too familiar with the details of the runtime PM API, but if
you can make this a barrier to prevent the host to call too many
suspends/resumes in a row, that would be nice.
And we might be able to ditch I2C_HID_QUIRK_DELAY_AFTER_SLEEP and
I2C_HID_QUIRK_NO_RUNTIME_PM.

Adding the involved people in the thread.

Cheers,
Benjamin

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