Re: [PATCH V3 2/2] pinctrl: tegra: Add driver to configure voltage and power of io pads

[Linus Walleij <linus.walleij@linaro.org>]

On Tue, Nov 22, 2016 at 11:20 AM, Laxman Dewangan <ldewangan@nvidia.com> wrote:

> NVIDIA Tegra124 and later SoCs support the multi-voltage level and
> low power state of some of its IO pads. The IO pads can work in
> the voltage of the 1.8V and 3.3V of IO voltage from IO power rail
> sources. When IO interfaces are not used then IO pads can be
> configure in low power state to reduce the power consumption from
> that IO pads.
>
> On Tegra124, the voltage level of IO power rail source is auto
> detected by hardware(SoC) and hence it is only require to configure
> in low power mode if IO pads are not used.
>
> On T210 onwards, the auto-detection of voltage level from IO power
> rail is removed from SoC and hence SW need to configure the PMC
> register explicitly to set proper voltage in IO pads based on
> IO rail power source voltage.
>
> This driver adds the IO pad driver to configure the power state and
> IO pad voltage based on the usage and power tree via pincontrol
> framework. The configuration can be static and dynamic.
>
> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>

Overall very nice!

> +               rinfo->regulator = devm_regulator_get_optional(dev,
> +                                               soc_data->cfg[i].vsupply);

Please just use devm_regulator_get().

As has been discussed at lenth elsewhere "optional" in regulator_get_optional
does *not* mean "software optional", it means "hardware optional".

Such as a terminal that may have a voltage connected or not be
connected to anything at all.

If the system does not define a regulator you will anyway get a
dummy regulator.

Yours,
Linus Walleij