Re: [Bug 203297] Synaptics touchpad TM-3127 functionality broken by PCI runtime power management patch on 4.20.2

Jean Delvare
2019-04-29T09:45:47Z

On Mon, 2019-04-29 at 10:53 +0200, Benjamin Tissoires wrote:
> On Mon, Apr 29, 2019 at 10:38 AM Jarkko Nikula
> <jarkko.nikula@linux.intel.com> wrote:
> > I got another thought about this. I noticed these input drivers need
> > SMBus Host Notify, maybe that explain the PM dependency? If that's the
> > only dependency then we could prevent the controller suspend if there is
> > a client needing host notify mechanism. IMHO that's less hack than the
> > patch to rmi_smbus.c.
>
> So currently, AFAIK, only Synaptics (rmi4) and Elantech are using
> SMBus Host Notify.
> So this patch would prevent the same bugs for those 2 vendors, which is good.
>
> It took me some time to understand why this would be less than a hack.
> And indeed, given that Host Notify relies on the I2C connection to be
> ready for the IRQ, we can not put the controller in suspend like we do
> for others where the IRQ controller is still ready.
>
> So yes, that could work from me. Not sure what Wolfram and Jean would
> say though.

I would say OK with me, this looks like the cleanest solution to me, so
if testing is positive, let's go with it.

--
Jean Delvare
SUSE L3 Support