Re: [PATCH -next 1/2] i2c: designware: Switch from using MMIO access to SMN access

Hans de Goede
2022-09-22T14:30:03Z

Hi,

On 9/22/22 16:04, Borislav Petkov wrote:
> On Thu, Sep 22, 2022 at 03:48:07PM +0200, Hans de Goede wrote:
>> Right, thank you for Cc-ing me. At least on X86 there are several platforms
>> (and 100-s of device models) which use a PMIC connected to the i2c-designware
>> controller and this PMIC gets poked directly from ACPI _S0 and _S3
>> (power on/off) methods. So the I2C bus driver needs to *bind* to the controller
>> as soon as we find its description in ACPI, otherwise we get a whole bunch
>> of failed ACPI OpRegion access errors as well as various actual really issues.
>
> Thanks for explaining - I couldn't find the reason why it has to be a
> subsys_initcall.
>
>> So please keep this as a subsys initcall.
>
> Which means, init_amd_nbs() would have to be sorted to run before
> dw_i2c_init_driver()...

Yes if possible. One solution might be to make it a arch_initcall_sync()
which AFAIK runs after regular arch_initcall()-s but before subsys_initcall()-s.

Regards,

Hans