Re: [PATCH v2] ACPI / LPSS: Don't abort acpi scan on missing mem resource.

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Wed, Aug 09, 2017 at 01:15:42AM -0700, Ronald Tschalär wrote:
> The keyboard and touchpad on MacBook's from 2015 onwards are connected
> via an SPI bus. On MacBook8's (2015) the ACPI device for the SPI master
> for this bus has _CID "INT33C1", and hence the acpi-lpss handler here is
> triggered for it. However, the DSDT lists no memory resources for this
> device, resulting in an error being returned by the attach callback and
> therefore the SPI master device being ignored. This prevents us from
> being able to register the keyboard and touchpad driver.
> 
> Furthermore, the controller (a Wildcat Point-LP controller) does not
> appear to need the functionality provided by the apci-lpss handler.
> Therefore we now just skip the handler if no memory resources are found
> and let the ACPI scan complete successfully for this device.
> 
> All of this is not an issue on later MacBook(Pro)'s because their ACPI
> SPI devices don't have any _CID and therefore no attempt is made to attach
> this handler.
> 
> Returning an error was introduced in commit d3e13ff3c1aa - this restores
> the original behaviour.
> 
> Link: https://github.com/cb22/macbook12-spi-driver
> Signed-off-by: Ronald Tschalär <ronald@innovation.ch>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>