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

[Marek Vasut]

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