Re: [PATCH 6/6] platform/x86: dell-smo8800: Add support for probing for the accelerometer i2c address

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

Hi,

On 1/5/24 19:51, Pali Rohár wrote:
> On Friday 05 January 2024 17:36:03 Hans de Goede wrote:
>> Hi Pali,
>>
>> On 12/24/23 23:07, Pali Rohár wrote:
>>> On Sunday 24 December 2023 22:36:22 Hans de Goede wrote:
>>>> Unfortunately the SMOxxxx ACPI device does not contain the i2c-address
>>>> of the accelerometer. So a DMI product-name to address mapping table
>>>> is used.
>>>>
>>>> At support to have the kernel probe for the i2c-address for modesl
>>>> which are not on the list.
>>>>
>>>> The new probing code sits behind a new probe_i2c_addr module parameter,
>>>> which is disabled by default because probing might be dangerous.
>>>>
>>>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>>>
>>> I would really like to hear Dell opinion about this change, and if there
>>> is really no way to get i2c address. Could you ask Dell people about it?
>>> Always it is better to use official / vendor provided steps of hardware
>>> detection, instead of inventing something new / own which would be there
>>> for a long time...
>>
>> Unfortunately I no longer have any contacts inside Dell for
>> this and given Dell's non response in the original thread
>> which started this I'm not hopefull for help from Dell here.
> 
> Well, writing an email to hundred of receivers, or writing 10 or more
> emails at the same time is nowadays an example how to get your email
> into spam box in lot of companies.
> 
>> Also there original reaction indicated that the info is not
>> available in ACPI, so probing + extending the DMI match
>> list seems to be the only way.
> 
> I have verified this statement years ago and therefore it applies only
> for old models (about 10 years old). So using this statement is not
> valid for new models anymore.

The latest Dell model which I have which still has a SM088xx ACPI
device is a Dell XPS 15 9550 from ~2016 this one still only has
an interrupt resource for the SMO8810 ACPI device and no 
I2cSerialBus[V2] resource.

On my Dell XPS 15 9550 the SMO8810 ACPI device is disabled,
still the accelerometer is actually there, but the IRQ is not setup
by the BIOS. So it can only work as an accelerometer and not
for /dev/freefall, likely because my model has the big battery
which covers the room for a 2.5" sata disk, so the freefall
function is disabled in the BIOS.

I have a patch series to still make the accelerometer work
on the XPS 15 9550 even though it is disabled in the BIOS,
but first lets get this series merged and then I'll send
the XPS 15 9550 series to be applied on top later.

Regards,

Hans