Re: [PATCH] mmc: meson: initial ocr available by default value

[Martin Blumenstingl]

On Mon, Dec 13, 2021 at 2:25 PM Jerome Brunet <jbrunet@xxxxxxxxxxxx> wrote:
>
>
> On Mon 13 Dec 2021 at 19:50, "rong.chen@xxxxxxxxxxx" <rong.chen@xxxxxxxxxxx> wrote:
>
> > Hello,
> > If 3.3V always-on power source for vmmc is supplied by hardware boards fixed, don't need regulator in software, so  .dts unnecessary the link between regulator
> > and MMC controller vmmc/vqmmc.
>
> Controllable or not, your vmmc/vqmmc regulators should be described in
> DT.
I agree with Jerome. Here are the two reasons why I think that it's
best to describe these regulators in device-tree:
- device-tree is there to describe the hardware. It's especially
useful for non-discoverable information (USB and PCI IDs are
discoverable examples), for example: voltage supply of an MMC
controller, UART IRQ line, ...
- reviewing board.dts would be a lot harder if we rely on defaults
(defaults which cannot be described in a device-tree schema). For
meson-g12a-radxa-zero.dts this means we could omit the vmmc/vqmmc
regulators for the SD card slot but we need them for the eMMC (because
vqmmc is fixed at 1.8V).


Best regards,
Martin