Hi Fabio,
On Fri, May 14, 2021 at 9:30 AM Fabio Estevam festevam@gmail.com wrote:
Hi Andrey,
On Wed, May 12, 2021 at 6:47 PM ZHIZHIKIN Andrey andrey.zhizhikin@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?
Maybe a dynamic way to identify if BD71837 or PCA9450 (by probing i2c) would work better?
Different configs would imply different builds and binaries, which is a problem when trying to support a single build for both the old EVK and EVKB (and the main difference is the PMIC, nothing really major).
I also share Andrey's concerns, as we do have several EVKs in hands, and having one single build would facilitate quite a bit.
Cheers,