[U-Boot] [PATCH v4 13/19] sunxi: DT: A64: update board .dts files from Linux

[André Przywara]

On 23/03/18 18:14, Jagan Teki wrote:
> On Wed, Mar 14, 2018 at 7:27 AM, Andre Przywara <andre.przywara at arm.com> wrote:
>> Update the .dts files for the various boards with an Allwinner A64 SoC.
>> This is as of v4.15-rc9, exactly Linux commit:

....

>>
>>  &mmc2 {
>>         pinctrl-names = "default";
>>         pinctrl-0 = <&mmc2_pins>;
>> -       vmmc-supply = <&reg_vcc3v3>;
>> +       vmmc-supply = <&reg_dcdc1>;
> 
> These AXP regulator stuff need to wait until the relevant driver
> supported through dt

Well, we could take the two patches I had in v3 that revert this change.
As mentioned before, DCDC1 is an always-on regulator anyways.

But actually that's not our problem, as we don't define DM_REGULATORS,
so we will never parse those properties.

Instead:

> otherwise moving to DM_MMC might fail to get the
> regulator? [1]
> [1] https://patchwork.ozlabs.org/patch/887405/

Ah, thanks for the link, I totally missed that.
So as Heinrich rightfully feared in his first patch, this change - for
all sunxi boards - breaks most of them: The DM-MMC part of the sunxi MMC
driver is not ready for any other SoC than the A20:
a) The only compatible string it knows is "allwinner,sun5i-a13-mmc".
b) It assumes the old style clocks, even without checking if the
referenced nodes are compatible.

So while a) is trivial to fix (U-Boot probably does not need to care
about the differences in the MMC controllers of the different SoCs), b)
is more of a beast.
I started looking into an easy implementation of the new clocks,
basically just enough to get MMC going, for the H3/H5 and A64. This
could be extended for other clocks once we need them.
But I am afraid this is not 2018.05 material anymore.

So what do we do here?

1) Just switch over A20? The A20 DTs in U-Boot use the old-style clocks
still, so that's fine. And we postpone the DM-MMC switch for the rest
until we have some DM new-style clock driver?
2) Push forward on some simple sunxi-ng MMC clock driver?
3) Don't use DM_MMC at all?

Would love to here other's opinions.

Cheers,
Andre.