[PATCH v2 2/2] mx7ulp: Only enable LDO if it is not already enabled

Fabio Estevam
2020-02-03T12:13:40Z

Hi Peng,

On Mon, Feb 3, 2020 at 9:07 AM Peng Fan <peng.fan@nxp.com> wrote:

> Just have a question, LDO mode enabled by ROM, this is configured with fuse?

I looked at the fuse map and did not see a fuse that controls it.

> Is there any special configuration need to be done in Linux? I not touch this
> part before (:

In LDO-enabled mode cpufreq needs to be disabled.

Please see:
https://github.com/fabioestevam/linux-imx/commit/8d66e5aae5b32261c9e2757c3844438c98ed0dfe

The reason is that in LDO-enabled mode only RUN mode at 500MHz is supported.

HSRUN at 720MHz is not supported in LDO-enabled mode, so ROM boots at
500MHz and kernel keeps always running at this frequency.

Regards,

Fabio Estevam

>
> Thanks,
> Peng.
>
> > ---
> > Changes since v1:
> > - Drop the define changes as they are duplicated (Stefano).
> >
> > arch/arm/mach-imx/mx7ulp/soc.c | 25 ++++++++++++++-----------
> > 1 file changed, 14 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/arm/mach-imx/mx7ulp/soc.c
> > b/arch/arm/mach-imx/mx7ulp/soc.c index d8d691692c..0d39dab7ea 100644
> > --- a/arch/arm/mach-imx/mx7ulp/soc.c
> > +++ b/arch/arm/mach-imx/mx7ulp/soc.c
> > @@ -118,12 +118,26 @@ void init_wdog(void)
> > disable_wdog(WDG2_RBASE);
> > }
> >
> > +static bool ldo_mode_is_enabled(void)
> > +{
> > + unsigned int reg;
> > +
> > + reg = readl(PMC0_BASE_ADDR + PMC0_CTRL);
> > + if (reg & PMC0_CTRL_LDOEN)
> > + return true;
> > + else
> > + return false;
> > +}
> > +
> > #if !defined(CONFIG_SPL) || (defined(CONFIG_SPL) &&
> > defined(CONFIG_SPL_BUILD)) #if defined(CONFIG_LDO_ENABLED_MODE)
> > static void init_ldo_mode(void) {
> > unsigned int reg;
> >
> > + if (ldo_mode_is_enabled())
> > + return;
> > +
> > /* Set LDOOKDIS */
> > setbits_le32(PMC0_BASE_ADDR + PMC0_CTRL,
> > PMC0_CTRL_LDOOKDIS);
> >
> > @@ -193,17 +207,6 @@ const char *get_imx_type(u32 imxtype)
> > return "7ULP";
> > }
> >
> > -static bool ldo_mode_is_enabled(void)
> > -{
> > - unsigned int reg;
> > -
> > - reg = readl(PMC0_BASE_ADDR + PMC0_CTRL);
> > - if (reg & PMC0_CTRL_LDOEN)
> > - return true;
> > - else
> > - return false;
> > -}
> > -
> > int print_cpuinfo(void)
> > {
> > u32 cpurev;
> > --
> > 2.17.1
>