Re: [PATCH 3/3] ACPI / X86: Add KIOX000A accelerometer on GPD win to always_present_ids array

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

Hi,

On 10-07-17 12:29, Andy Shevchenko wrote:
> On Mon, 2017-07-10 at 12:25 +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 10-07-17 12:22, Andy Shevchenko wrote:
>>> On Sun, 2017-07-09 at 21:05 +0200, Hans de Goede wrote:
>>>> The GPD win BIOS dated 20170320 has disabled the accelerometer,
>>>> the
>>>> drivers sometimes cause crashes under Windows and this is how the
>>>> manufacturer has solved this :|
>>>>
>>>> I see no other way to keep the accelerometer working under Windows
>>>> then
>>>> adding it to the always_present_ids array.
>>>>
>>>> +	ENTRY("KIOX000A", "1", ICPU(INTEL_FAM6_ATOM_AIRMONT), {
>>>> +		DMI_MATCH(DMI_BOARD_VENDOR, "AMI Corporation"),
> 
>>>> +		DMI_MATCH(DMI_BOARD_NAME, "Default string"),
>>>> +		DMI_MATCH(DMI_PRODUCT_NAME, "Default string"),
> 
> Just noticed above, don't think it's a good idea to place kinda defaults
> there.

That is why there is a comment above the entry:

         /*
          * The GPD win BIOS dated 20170320 has disabled the accelerometer, the
          * drivers sometimes cause crashes under Windows and this is how the
          * manufacturer has solved this :| Note that the the DMI data is less
          * generic then it seems, a board_vendor of "AMI Corporation" is quite
          * rare and a board_name of "Default String" also is rare.
          */

Most Cherry Trail BIOS-es (and we do a CPU-id check for Cherry Trail)
have both DMI_BOARD_NAME and DMI_PRODUCT_NAME set to something more
sensible then "Default string" and other then the GPD win / pocket no
other model that I know of has a DMI_BOARD_NAME of "Default string"

So we can be pretty sure that the combination of Cherry Trail CPU +
these DMI strings + a BIOS-date of "03/20/2017" + having an ACPI
device with a HID of KIOX000A" is unique.

Also note that even if we have a false positive, the KIOX000A driver
will fail with a probe error, unless there is an other i2c device at
the exact same address.

Regards,

Hans