Re: [PATCH] i2c: core: Call i2c_acpi_install_space_handler() before i2c_acpi_register_devices()

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 9/9/20 12:32 PM, Hans de Goede wrote:
> 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@redhat.com>

Ping? This fixes a serious problem (non working touchpad on various
laptop models) and is a pretty straight-forward fix.

Arguably it should even go to stable, but I'm not 100% sure about that
because these sorta ACPI enumeration problems can sometimes by
tricky. With that said in this case the fix does seem to be
very straight forward and obviously correct.

Mika, since this deals with the ACPI bits of the i2c-core can
you review this one please?

Regards,

Hans


> ---
>   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 5ec082e2039d..573b5da145d1 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1464,8 +1464,8 @@ 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);
>