Re: [PATCH AUTOSEL 5.8 17/20] i2c: core: Call i2c_acpi_install_space_handler() before i2c_acpi_register_devices()

[Hans de Goede]

Hi,

On 10/14/20 1:09 PM, Kieran Bingham wrote:
> Hi Hans, Sasha,
>
> As mentioned on https://github.com/linux-surface/kernel/issues/63, I'm
> afraid I've bisected a boot time issue on the Microsoft Surface Go 2 to
> this commit on the stable 5.8 tree.
>
> The effect as reported there is that the boot process stalls just after
> loading the usbhid module.
>
> Typing, or interacting with the Keyboard (Type Cover) at that point
> appears to cause usb bus resets, but I don't know if that's a related
> symptom or just an effect of some underlying root cause.
>
> I have been running a linux-media kernel on this device without issue.
>
> Is this commit in 5.9? I'll build a vanilla v5.9 kernel and see if it
> occurs there too.

Yes the commit is in 5.9 too. Still would be interesting to see if 5.9 hits
this issue too. I guess it will, but as I mentioned in:

https://github.com/linux-surface/kernel/issues/63

I do not understand why this commit is causing this issue.

So I just checked and the whole acpidump is not using I2C
opregion stuff at all:

[hans@x1 microsoft-surface-go2]$ ack GenericSerialBus *.dsl
[hans@x1 microsoft-surface-go2]$

And there is only 1 _REG handler which is for the
embedded-controller.

So this patch should not make a difference at all on the GO2,
other then maybe a subtle timing difference somewhere ... ?

Regards,

Hans


> On 21/09/2020 15:40, Sasha Levin wrote:
> > From: Hans de Goede <hdegoede@xxxxxxxxxx>
> >
> > [ Upstream commit 21653a4181ff292480599dad996a2b759ccf050f ]
> >
> > Some ACPI i2c-devices _STA method (which is used to detect if the device
> > is present) use autodetection code which probes which device is present
> > over i2c. This requires the I2C ACPI OpRegion handler to be registered
> > before we enumerate i2c-clients under the i2c-adapter.
> >
> > This fixes the i2c touchpad on the Lenovo ThinkBook 14-IIL and
> > ThinkBook 15 IIL not getting an i2c-client instantiated and thus not
> > working.
> >
> > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1842039
> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >   drivers/i2c/i2c-core-base.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> > index 4f09d4c318287..7031393c74806 100644
> > --- a/drivers/i2c/i2c-core-base.c
> > +++ b/drivers/i2c/i2c-core-base.c
> > @@ -1336,8 +1336,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
> >   
> >   	/* create pre-declared device nodes */
> >   	of_i2c_register_devices(adap);
> > -	i2c_acpi_register_devices(adap);
> >   	i2c_acpi_install_space_handler(adap);
> > +	i2c_acpi_register_devices(adap);
> >   
> >   	if (adap->nr < __i2c_first_dynamic_bus_num)
> >   		i2c_scan_static_board_info(adap);