From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabio Estevam Date: Fri, 14 May 2021 09:30:30 -0300 Subject: [PATCH 03/26] imx8mm_evk: Switch to new imx8mm evk board In-Reply-To: References: <20210319075718.14181-1-peng.fan@oss.nxp.com> <20210319075718.14181-4-peng.fan@oss.nxp.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Andrey, On Wed, May 12, 2021 at 6:47 PM ZHIZHIKIN Andrey 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