Re: [Letux-kernel] [RFC PATCH 0/3] Enable 1GHz support on omap36xx

["H. Nikolaus Schaller" <hns@goldelico.com>]

Hi,

> Am 11.09.2019 um 14:43 schrieb Adam Ford <aford173@gmail.com>:
> 
>> 
>> I can also see that there are transitions on the voltages (reg.8 is vdd and reg.3 is abb).
> 
> I concur.  I have good results with the added ti,omap-opp-supply entry.

Great!

There are some subtleties for testing.

* I have added turbo-mode; to OPP6 / OPP1G
* which means they are available but not used by the ondemand govenor
* to enable them one has to echo 1 >/sys/devices/system/cpu/cpufreq/boost

Testing is also easily done through cpufreq-set -f 800m or-f 1g

Then I can see the microvolts change and also registers
PRM_LDO_ABB_CTRL 0x483072F4 bit 3:0 1=bypass 5=FBB
PRM_LDO_ABB_SETUP 0x483072F0 0x00=bypass 0x11=FBB

I have added both of this as descriptive notes to the commit messages.

What I have to check is if it behaves as expected on a dm3730 without
1GHz rating.

> I noticed the FIXME note on the omap36xx.dtsi file where you added the
> vdd-supply reference.  For what its worth, I searched for a list of
> all files that reference omap3630, then built a bunch of dtb's
> 
> make `cat dtb-list` ARCH=arm CROSS_COMPILE="ccache arm-linux-" -j8
>  DTC     arch/arm/boot/dts/omap3-beagle-xm.dtb
>  DTC     arch/arm/boot/dts/omap3-cm-t3730.dtb
>  DTC     arch/arm/boot/dts/omap3-evm-37xx.dtb
>  DTC     arch/arm/boot/dts/omap3-igep0020.dtb
>  DTC     arch/arm/boot/dts/omap3-igep0020-rev-f.dtb
>  DTC     arch/arm/boot/dts/omap3-igep0030.dtb
>  DTC     arch/arm/boot/dts/omap3-igep0030-rev-g.dtb
>  DTC     arch/arm/boot/dts/omap3-lilly-dbb056.dtb
>  DTC     arch/arm/boot/dts/omap3-n950.dtb
>  DTC     arch/arm/boot/dts/omap3-n9.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-alto35.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-chestnut43.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-gallop43.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-palo35.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-palo43.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-summit.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-tobi.dtb
>  DTC     arch/arm/boot/dts/omap3-overo-storm-tobiduo.dtb
>  DTC     arch/arm/boot/dts/omap3-pandora-1ghz.dtb
>  DTC     arch/arm/boot/dts/omap3-sbc-t3730.dtb
>  DTC     arch/arm/boot/dts/omap3-sniper.dtb
>  DTC     arch/arm/boot/dts/omap3-zoom3.dtb
>  DTC     arch/arm/boot/dts/omap3-gta04a5.dtb
>  DTC     arch/arm/boot/dts/omap3-gta04a5one.dtb
>  DTC     arch/arm/boot/dts/omap3-gta04a3.dtb
>  DTC     arch/arm/boot/dts/omap3-gta04a4.dtb

Quite a lot...

> I think it's probably safe to leave the vcc-supply there, but you may
> want to add a note that users who do not use twl4030 should add
> something to their device tree to specify the vcc-supply.
> 
> At this point, I doubt anyone will do new designs on omap3 SoC's.

Well, I am not sure if there are out-of-tree boards with omap3
where we could break everything. I know of at least one such
board.

Therefore I have looked where the cpu0-supply vs. vdd-supply
is decoded. It turns out to be also the ti-cpufreq driver
which we already tweak for omap3 support.

So I just have to modify ca. 10 LOC to add this "cpu0" to the
SoC description tables and process it once during probe time.

Then, it works with unmodified board.dtb
defining cpu0-supply = <&vcc> or whatever regulator.

The only question that comes up is if this change is am3517
compatible. I.e. can we still use the omap36xx_soc_data for
it as well which now expects two regulators... So you
might now see an error message that cpu0-supply and vbb-supply
are missing or not the right number of regulators is given.

We may have to add an am3517_soc_data table, but that would
be straightforward now.

> 
>> so that you can inspect/compare/test/check before I tidy up and add
>> the patches for our OPP-v2 patch set.
> 
> I think it looks good.  Maybe Tony and or TI people have some
> comments, but it appears to set both regulators now.
> 
> Nice job!

With your kind help!

Now it's time to wrap up and post a new PATCH set version for
review.

Best regards,
Nikolaus