[PATCH 1/3]: Support cpu frequency scaling and power management for iMX6SL

[Shawn Guo]

On Tue, Dec 17, 2013 at 07:30:46PM +0100, Markus Niebel wrote:
> >> @@ -38,6 +38,19 @@
> >>                         device_type = "cpu";
> >>                         reg = <0x0>;
> >>                         next-level-cache = <&L2>;
> >> +                       operating-points = <
> >> +                               /* kHz    uV */
> >> +                               1000000 1275000
> >> +                               792000  1150000
> 
> according to the CPU documentation the following operation points are suggested (at least AFAIK):
>                                996000  1250000 /* for consumer grade only */
>                                792000  1150000
>                                396000  1050000
> note: AFAIK there is no way to detect at runtime if we  running on industrial / automotive variant
> so there is a risk to run at too high frequency ...

I can only find IMX6SLCEC - i.MX 6SoloLite Applications Processors for
Consumer Products on freescale website.

 http://cache.freescale.com/files/32bit/doc/data_sheet/IMX6SLCEC.pdf?fpsp=1

In that document, I can see the following in Table 9. Operating Ranges.

 LDO output set at 1.250V minimum for operation up to 996MHz
 LDO output set at 1.150V minimum for operation up to 792MHz
 LDO output set at 0.95V minimum for operation up to 396MHz

However, if you access Freescale 3.10 kernel tree, you will see there
are 25mV addition to each operating-point.

	operating-points = <
		/* kHz   uV */
		996000  1275000
		792000  1175000
		396000  975000
	>;

>From the commit log, it said this 25mV is added to compensate the output
tolerance from external regulators.

I suggest we follow Freescale kernel to set the operating-points.

Shawn