[PATCH 2/2] mxs: Don't enable 4P2 reg if MXS is powered only from DCDC_BATT

[Lukasz Majewski]

Hi Marek, Cody,

> On 7/3/23 18:33, Cody Green wrote:
> > 'mxs_power_enable_4p2()' function call was added to
> > 'mxs_batt_boot()' in 'commit a0f97610757d' 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:
> > 
> >    setbits_le32(&power_regs->hw_power_vddioctrl,
> >      POWER_VDDIOCTRL_DISABLE_FET | POWER_VDDIOCTRL_PWDN_BRNOUT);
> > 
> > There is no issue if the MXS is powered from the 5V source and
> > linear regulators are supplying power to the VDDIO, VDDA, VDDD
> > rails. However, if the MXS is powered only from the DCDC_BATT
> > without 5V, disabling the DCDC converter outputs causes VDDIO,
> > VDDA, VDDD rails to lose power.

I think that I've also hit the same issue with the XEA board
(upstreamed).

I've prepared a set of patches:
https://patchwork.ozlabs.org/project/uboot/patch/20230509143243.1523791-5-lukma@denx.de/

to fix this problem.

Those patches are now for some time on the mailing list for review - and
I do hope that Stefano will pull them with next PR for u-boot-imx
repository.

> > 
> > The proposed solution is not to call the 'mxs_power_enable_4p2()'
> > function if the MXS is powered only by the DCDC_BATT, because there
> > is no reason to enable 4P2 regulator in this case.

I think this patch:
https://patchwork.ozlabs.org/project/uboot/patch/20230509143243.1523791-3-lukma@denx.de/

address exactly this issue.

> > Also 5V brownout
> > should not be enabled in 'mxs_power_init()' and linear regulator
> > checks should be disabled in 'mxs_power_set_vddx()'.
> > 

I've also added some code to limit the VDD5V current when we intend to
use DCDC_BATT input as the _primary_ source of power (AN4199 advises
this one for industrial applications as the most reliable).


> > Signed-off-by: Cody Green <cody at londelec.com>
> > Cc: Stefano Babic <sbabic at denx.de>
> > Cc: Marek Vasut <marex at denx.de>
> > Cc: Fabio Estevam <festevam at gmail.com>
> > ---
> >   arch/arm/cpu/arm926ejs/mxs/spl_power_init.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> > 
> > diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
> > b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c index
> > 33b76533e4..72172705f2 100644 ---
> > a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c +++
> > b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c @@ -752,7 +752,9 @@
> > static void mxs_batt_boot(void) POWER_5VCTRL_CHARGE_4P2_ILIMIT_MASK,
> >   		0x8 << POWER_5VCTRL_CHARGE_4P2_ILIMIT_OFFSET);
> >   
> > +#ifndef CFG_SPL_MXS_NO_VDD5V_SOURCE
> >   	mxs_power_enable_4p2();
> > +#endif
> >   }
> >   
> >   /**
> > @@ -1137,8 +1139,11 @@ static void mxs_power_set_vddx(const struct
> > mxs_vddx_cfg *cfg, cur_target += cfg->lowest_mV;
> >   
> >   	adjust_up = new_target > cur_target;
> > +
> > +#ifndef CFG_SPL_MXS_NO_VDD5V_SOURCE
> >   	if (cfg->powered_by_linreg)
> >   		powered_by_linreg = cfg->powered_by_linreg();
> > +#endif
> >   
> >   	if (adjust_up && cfg->bo_irq) {
> >   		if (powered_by_linreg) {
> > @@ -1269,7 +1274,9 @@ void mxs_power_init(void)
> >   		POWER_CTRL_VBUS_VALID_IRQ |
> > POWER_CTRL_BATT_BO_IRQ | POWER_CTRL_DCDC4P2_BO_IRQ,
> > &power_regs->hw_power_ctrl_clr); 
> > +#ifndef CFG_SPL_MXS_NO_VDD5V_SOURCE
> >   	writel(POWER_5VCTRL_PWDN_5VBRNOUT,
> > &power_regs->hw_power_5vctrl_set); +#endif
> >   
> >   	early_delay(1000);
> >   }  
> 
> +CC Lukasz




Best regards,

Lukasz Majewski

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