Subject: Device tree binding for DVFS table

From: [email-masked] (Mike Turquette)
Date: Wed, 11 Jul 2012 13:04:02 -0700

On 20120711-15:44, Mark Brown wrote:
> On Wed, Jul 11, 2012 at 09:03:41AM -0500, Rob Herring wrote:
> 
> > I'd expect a single property with freq/volt pairs or 2 properties for
> > freq and voltage where there is a 1:1 relationship (freq N uses voltage N).
> 
> I strongly agree - the current proposal is very hard to read due to the
> separation between the voltage and frequency values.  Some devices do
> also need to scale multiple rails together, especially when this gets
> used for I/O devices.
> 
> I'd also expect to see a range of voltages for each frequency rather
> than a specific voltage; usually things are at least characterised with
> a specified tolerance.

Not only should we support multiple voltage rails but also multiple
clocks.  For some devices a DVFS transition is composed of scaling
multiple clock rates together.  So some sort of clock identifier
(phandle?) is needed as well.  (forgive my ignorance on the phandle
part, as I am a DT noob)

Regards,
Mike