question: mx7ulp - LDO_ENABLED_MODE

[Fabio Estevam]

Hi Jorge,

On Thu, Jan 16, 2020 at 5:30 PM Jorge Ramirez-Ortiz, Foundries
<jorge at foundries.io> wrote:
>
> Hi Fabio,
>
> I am trying to enable LDO in an imx7ulp based board but somehow the
> board locks up as soon I  write to PMC1_RUN (using the init_ldo_mode
> sequence).

Just looked at the i.MX7UL Reference Manual and it says:

"28.5.9.1.1 Using internal LDO regulator
After a POR event, when the PMC 0 is running in RUN mode and the PMC 1 is turned
off, the process to turn on the PMC 1 using the internal LDO regulator
is as follows:
• Assert the LDOEN bit (PMC0_CTRL).
• Assert the LDOOKDIS bit (PMC0_CTRL) if required.
• Assert the PMC1ON bit (PMC0_CTRL)."

So it seems we need to change the order to:

--- a/arch/arm/mach-imx/mx7ulp/soc.c
+++ b/arch/arm/mach-imx/mx7ulp/soc.c
@@ -122,9 +122,6 @@ static void init_ldo_mode(void)
 {
        unsigned int reg;

-       /* Set LDOOKDIS */
-       setbits_le32(PMC0_BASE_ADDR + PMC0_CTRL, PMC0_CTRL_LDOOKDIS);
-
        /* Set LDOVL to 0.95V in PMC1_RUN */
        reg = readl(PMC1_BASE_ADDR + PMC1_RUN);
        reg &= ~PMC1_LDOVL_MASK;
@@ -151,6 +148,9 @@ static void init_ldo_mode(void)
        /* Set LDOEN bit */
        setbits_le32(PMC0_BASE_ADDR + PMC0_CTRL, PMC0_CTRL_LDOEN);

+       /* Set LDOOKDIS */
+       setbits_le32(PMC0_BASE_ADDR + PMC0_CTRL, PMC0_CTRL_LDOOKDIS);
+
        /* Set the PMC1ON bit */
        setbits_le32(PMC0_BASE_ADDR + PMC0_CTRL, PMC0_CTRL_PMC1ON);
 }

Does this help?

> I think it is interesting that bit PMC0_CTRL_PMC1ON is already set so
> I am wondering if you think it is possible - in your experience- that
> ROM might have already configured LDO? or was this also the case -
> this bit already set- when you tested the feature?

I think it was not set by default. I can confirm tomorrow with a
i.MX7ULP Embedded Artists board.

Regards,

Fabio Estevam