[PATCH 03/26] imx8mm_evk: Switch to new imx8mm evk board

[Fabio Estevam]

Hi Andrey,

On Wed, May 12, 2021 at 6:47 PM ZHIZHIKIN Andrey
<andrey.zhizhikin at leica-geosystems.com> wrote:

> > Update PMIC to use PCA9540, the legacy board not supported by NXP
>
> This commit seems rather a "nuclear" to me, as de-facto it drops the initialization of ROMH PMIC in
> favor of PCA one, leaving all the previous board revisions not to be properly sourced.
>
> I know that there might be no intention to provide a support for earlier revisions of i.MX8M Mini
> EVKs from NXP, but providing no backward compatibility to those boards which are still in use by
> a lot of people for development purposes is highly undesirable either.
>
> TBH, I've tested this patch on the old EVK where ROMH PMIC is present, and apart from having some
> error messages in SPL regarding the register writes - it does boots. What worries me the most though
> is that DTS changes some voltage settings, which I'm not sure how the SOC would react on.
>
> To my opinion, this patch should either be complemented with the mechanism to provide a
> level of backward compatibility (where the PMIC can be dynamically identified and instantiated),
> or the separate implementation should be presented which would make the old board type not to
> be bootable at all if it is considered not to be supported any longer. Or this patch should be reverted
> in an effort to come up with a solution which covers new revision without "damaging" the currently
> integrated one.
>
> Fabio / Stefano,
> Do you have any thoughts here on how this should be handled further, considering the fact that the
> backward compatibility of 2021.07 release is not kept for this board type across multiple revisions?
>
> I'd really like to get your opinion here as I do have those boards in development and would need to
> come up with the idea on what to do with them.
>
> Also, this should be taken care of in the Yocto, since there is only one definition of the i.MX8MM EVK
> machine which does not make any distinction regarding the revision.

You bring a good point.

What about adding a new defconfig to support the old imx8mm-evk with
the Rohm PMIC?

Then we could have imx8mm_evk_defconfig for the new version and
imx8mm_evk_rohm_defconfig for the old one.

What do you think?

Thanks