Re: [PATCH] intel_scu_pcidrv: add back PCI id for Medfield

[Julian Winkler <julian.winkler1@web.de>]

On 17.04.23 12:16, Andy Shevchenko wrote:
> On Mon, Apr 17, 2023 at 1:11 PM Hans de Goede <hdegoede@redhat.com> wrote:
>> +Cc Andy, Mika,
>
> Thanks for Cc'ing me.
>
>> On 4/16/23 17:49, Julian Winkler wrote:
>>> This id was removed in b47018a778c1a18cbc98b4a11936dec4f8c4bb7b, saying it
>>> is only used on Moorestown, but apparently the same id is also used on
>>> Medfield.
>>>
>>> Tested on the Medfield based Motorola RAZR i smartphone.
>
> Wow! This is surprising.
> Can you tell more about your test environment? What is the Linux
> kernel version in use and what is the userspace (AOSP, Buildroot,
> Yocto, custom)? If custom, more details would be nice to hear.

The test enviroment is postmarketOS. You can find more details on the
Wiki page
https://wiki.postmarketos.org/wiki/Motorola_RAZR_i_(XT890)_(motorola-smi)

>>> Signed-off-by: Julian Winkler <julian.winkler1@web.de>
>>
>> Hmm, so this is a former SFI platform, from your:
>> https://lore.kernel.org/all/20230223060107.23029-1-julian.winkler1@web.de/
>>
>> patch I guess the plan is to use some custom bootloader
>> and then use x86 with devicetree support to replace SFI ?
>
> That would also be nice to hear in detail. With other Intel MID
> platforms the decision was made to pursue ACPI (and U-Boot, as an
> example) supports that for Intel Merrifield platform.

I boot a 5.10 kernel, which still has SFI support, and from there I can
boot latest mainline kernel with petitboot, kexec and devicetree.

>> Do you already have this working ?
>>
>> Sorry for all the questions for what is just a simple PCI-id
>> addition. I guess I'm worried this is just the tip of
>> the iceberg for getting medfield support back into
>> the kernel and I'm a bit worried about how much maintenance
>> work this will cause.
>>
>> E.g. also see commit e1da811218d2dc ("drm/gma500: Remove Medfield support")
>> which I guess you will want to see reverted too ?
>>
>> That is an example of a lot more code to bring back
>> then just a single PCI-id addition.
>>
>> Don't get me wrong I'm all for supporting older hw
>> if there are users who are interested in actively
>> maintaining support for it. I just want to get a feel
>> of the amount of work this is going to involve.
>>
>> Andy, Mika, any remarks ?
>
> I'm not against a patch if it helps existing users, but we need to
> understand first if it will be really helpful for upstream (taking
> into account 32-bit Intel MID support removal).

My downstream kernel tree can be seen here:
https://gitlab.com/julianwi/linux-intel-medfield. Indeed, I needed to
bring back some removed code to get the display working, but even
without display driver, old smartphones can be used as a server or
Raspberry Pi replacement.