On Tuesday 08 November 2016 09:16 PM, Linus Walleij wrote:

On Tue, Nov 8, 2016 at 2:35 PM, Laxman Dewangan [off-list ref] wrote:

quoted

There is two types of configuration in given platform, the IO voltage does
not get change (fixed in given platform) and in some of cases, get change
dynamically like SDIO3.0 where the voltage switches to 3.3V and 1.8V.

Yes, it can be integrated with the regulator handle and then it can call the
required configurations through notifier and regulator_get_voltage().
But I think it is too much complex for the static configurations. This
mandate also to populate the regulator handle and all power tree.

The simple way for static configuration (case where voltage does not get
change), just take the power tree IO voltage from DT and configure the IO
pad control register.

For dynamic case, there is some sequence need to be followed based on
voltage direction change (towards lower or towards higher) for the voltage
change and the IO pad voltage configuration and it is simple to do it from
client driver.

The devicetree should describe the platform.

Adding this custom attribute does not describe the platform very
well since the dependency to the corresponding regulator is hidden.

The point of device tree is not as much to make things simple as
to describe the world properly.

So to me it is simple: use regulators and phandles.

It might require a bit of upfront coding but the result will look
much nicer.

Oops, I asked same clarification when replying the Thierry's comment.

Got answer now.. only via regulator support.


I am going to support the IO pad voltage control with regulator only.
No custom attribute for this.
However, for support for low-power will be same as this patch.