linux-kernel - Re: [PATCH AUTOSEL 5.8 17/20] i2c: core: Call i2c_acpi_install_space_handler() before i2c_acpi_register

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Date:   Wed, 14 Oct 2020 12:09:09 +0100
From:   Kieran Bingham <kieran.bingham@...asonboard.com>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wolfram Sang <wsa@...nel.org>, linux-i2c@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.8 17/20] i2c: core: Call
 i2c_acpi_install_space_handler() before i2c_acpi_register_devices()

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.

--
Regards

Kieran


On 21/09/2020 15:40, Sasha Levin wrote:
> From: Hans de Goede <hdegoede@...hat.com>
> 
> [ 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@...hat.com>
> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Wolfram Sang <wsa@...nel.org>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  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);
> 


-- 
Regards
--
Kieran