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

[Cody Green]

'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);
 }
-- 
2.25.1