Re: [RFC PATCH] arm64: defconfig: Set MFD_TPS6594_I2C as built-in

[Judith Mendez]

Hello Nishanth,

Apologies for the late reply,

On 8/21/24 6:09 AM, Nishanth Menon wrote:
> On 09:42-20240820, Bjorn Andersson wrote:
> > On Mon, Aug 19, 2024 at 03:43:52PM -0500, Judith Mendez wrote:
> > > SK-AM62A-LP is a device targeting automotive front-camera applications
> > > among other use-cases. It utilizes the TPS6593x PMIC (interfaced over I2C)
> > > to power the SoC and various other peripherals on the board [1].
> > >
> > > MMCSD requires the PMIC to be setup correctly before setting the bus
> > > pins to 1.8V using the TPS6594 driver interfaced over i2c.
> > >
> > > Currently, the following could be seen when booting the am62ax platform:
> > >
> > > "platform fa00000.mmc: deferred probe pending: platform: supplier regulator-5 not ready"
> > > "vdd_mmc1: disabling"
> >
> > Is this the regulator framework disabling the "unused" vdd_mmc1 while
> > you still have a probe deferred client?
> >
> > That's not right.
>
> I think context of the full log might be missing, hence misleading - but
> if this is correct, regulator framework might have a problem as well -
> it does not change the fact that we will need regulator driver to
> support switch from 3.3v to 1.8v to enable UHS (which is another
> topic as well - do not trust the bootloader either for the default
> voltage enabled in the system).
>
> Judith: This is why providing links to previous versions of patches AND
> providing links to the full before and after logs in the diffstat
> section helps reviewers - please do that in the next revision.

Understood, will fix for v2.

> > > and a failure to boot the SK-AM62A-LP.
> > >
> > > One solution is to use initramfs [2], but using initramfs increases the
> > > boot time for this automotive solution which requires faster boot time
> > > parameters.
> > >
> > > Another solution is to change MFD_TPS6594_I2C to built-in, that way the
> > > PMIC is setup and the regulators are ready before MMCSD switches to UHS
> > > mode, this is the preferred solution since it does not increase boot time
> > > like the initramfs solution does.
>
> What is the adder in cost? bloat-o-meter report summary should have
> been part of commits that increase vmlinux

Will include in v2.

> > > [1] https://www.ti.com/lit/zip/sprr459
> > > [2] https://lore.kernel.org/linux-devicetree/5f03207b-c29b-4d16-92b0-d14eef77bf17@xxxxxxxxxx/
> > > Fixes: f9010eb938be ("arm64: defconfig: Enable TPS6593 PMIC for SK-AM62A")
> > >
> > > Signed-off-by: Judith Mendez <jm@xxxxxx>
> > > ---
> > >   arch/arm64/configs/defconfig | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> > > index 7d32fca649965..61f767246d3a5 100644
> > > --- a/arch/arm64/configs/defconfig
> > > +++ b/arch/arm64/configs/defconfig
> > > @@ -756,7 +756,7 @@ CONFIG_RZ_MTU3=y
> > >   CONFIG_MFD_TI_AM335X_TSCADC=m
> > >   CONFIG_MFD_TI_LP873X=m
> > >   CONFIG_MFD_TPS65219=y
> > > -CONFIG_MFD_TPS6594_I2C=m
> > > +CONFIG_MFD_TPS6594_I2C=y
> >
> > These things should work with =m, and then you can make them =y in your
> > product config to avoid the probe deferral.
>
> I think this is inline with the discussion with Krystoff on the topic as
> well
>
>
> Judith: you just need the regulator, for sd/mmc to work. Why is there
> half a dozen unrelated stuff coming with it [1] report from
> bloat-o-meter? Please fix the driver dependencies before adding
> un-necessary stuff to the kernel Image file.
>
> [1] https://gist.github.com/nmenon/0caff032a430bbf649ad1107e6f12f9a

Ok, will check this out, thanks for reviewing. (:

~ Judith

>