Hi Alan, [Adding Lukasz and Cody]
On Tue, Aug 30, 2022 at 2:49 PM Alan Kay <a...@londelec.com> wrote: > > mxs_power_enable_4p2() was added to mxs_batt_boot() in > 'commit a0f97610757d ("ARM: mxs: Enable DCDC converter for battery boot")' > to enable DCDC converter when board is powered from 5V and has > detected sufficient battery voltage. > This involves enabling 4P2 regulator and there is a code > in mxs_power_enable_4p2() that disables VDDIO, VDDA, VDDD outputs of > the DCDC converter and enables BO for each power rail e.g. > > setbits_le32(&power_regs->hw_power_vddioctrl, > POWER_VDDIOCTRL_DISABLE_FET | POWER_VDDIOCTRL_PWDN_BRNOUT); > > In case the mx28 is powered by the 5V source and linear regulators are > supplying power to the VDDIO, VDDA, VDDD rails there is no issue. > > However if the mx28 is powered by the DCDC_BATT source only without 5V, > disabling the DCDC converter outputs causes brownout power down. > > The proposed solution is not to call mxs_power_enable_4p2() at all > if the mx28 is powered by the DCDC_BATT source only. There is no > reason to enable 4P2 regulator in this case and setup of all registers > is done in mxs_batt_boot(). > > Also there is no need to enable 5V brownout in > mxs_power_init() in this case. > > Please consider if this is acceptable and I will submit a proper patch. > > Signed-off-by: Alan Kay <a...@londelec.com> Cody also sent a fix for this issue: https://patchwork.ozlabs.org/project/uboot/patch/20230703163340.101490-2-c...@londelec.com/