Re: [PATCH V2 4/6] DT: add binding for mxs on-chip regulators

["Jürgen Borleis" <jbe@pengutronix.de>]

Hi Stefan,

On Monday 04 May 2015 22:20:50 Stefan Wahren wrote:
> [...]
> >
> > +------------+     VDD5V  +---------+  VDDIO
> > | DC-DC      |   +--------> LINREG  +--------->+
> > |            |            | VDDIO   |          |
> > |            |            +---------+          |
> > |            |                                 |
> > | DCDC_VDDIO +->-+-----------------------------+
> > |            |   |
> > |            |   | VDDIO  +---------+ VDDMEM
> > |            |   +--------> LINREG  +--------->
> > |            |   |        | VDDMEM  |
> > |            |   |        +---------+
> > |            |   | VDDIO  +---------+  VDDA
> > |            |   +--------> LINREG  +--------->+
> > |            |            | VDDA    |          |
> > |            |            +---------+          |
> > | DCDC_VDDA  +->-+-----------------------------+
> > |            |   |
> > |            |   | VDDA   +---------+  VDDD
> > |            |   +--------> LINREG  +--------->+
> > |            |            | VDDD    |          |
> > |            |            +---------+          |
> > | DCDC_VDDD  +->-------------------------------+
> > +------------+                                 |
> >                                                v
>
> damn! I didn't noticed that VDDMEM is powered by VDDIO and VDD1P5 is
> powered by VDDA. Thank you very much.
>
> From my understanding VDDMEM and VDD1P5 describe the same regulator
> function (provides power to external memory such as SDRAM and mDDR which
> doesn't fit to VDDD, VDDIO or VDDA). But the usage of
> the name is not consistent across the documentation:
>                   | i.MX23 | i.MX28
> ------------------------------------
> Application note  | VDDMEM | VDD1P5
> Reference manual  | VDDMEM | VDDMEM
> Data sheet        | -      | VDD1P5
>
> I would suggest to use VDDMEM, because the registers are always called
> HW_VDDMEM (for both SoCs).

Ack.

> I think we have 3 options here:
>
> a) add the regulator daisy chain for the i.MX23 too
> b) remove VDD1P5 from the i.MX28 diagram so it would fit for both again
> c) remove the diagram complete
>
> I would prefer option b. What's your opinion?

I prefer a) because once the details are known, we should keep them.

Regards,
Juergen