On Tue, 11 Aug 2015, Viresh Kumar wrote:

On 11-08-15, 14:27, Lee Jones wrote:

quoted

Okay, so what you're saying is that you've already made the decision
to create a separate node for every OPP permutation,

Absolutely not.

quoted

despite the fact
that I've told you this could lead to more nodes than anyone would
care to successfully write or maintain?

I have enough fear of yours and then I have to see you in another
month as well. I wouldn't dare to disobey your command SIR :)

Funny guy! ;)

quoted

Perhaps an example might help explain the issue.

Using the current driver, we need to place the following in DT and the
driver does the rest:

opp-list {
	opp1 {
		opp-hz = <1500000000>;
		st,avs = <1200 1200 1200 1200 1170 1140 1100 1070>;
		st,substrate = <0xff>;
		st,cuts = <0xff>;
	};
	opp0 {
		opp-hz = <1200000000>;
		st,avs = <1110 1150 1100 1080 1040 1020 980 930>;
		st,substrate = <0xff>;
		st,cuts = <0x2>;
	};
};

Nothing is fixed as of now but this is what I am thinking of:

	cpu0_opp_table: opp_table0 {
		compatible = "operating-points-v2";
                opp-cuts = "10", "3c", "f0";
		supply-names = "vcc0", "vcc1", "vcc2";
		opp-shared;

		opp00 {
			opp-hz = /bits/ 64 <1000000000>;
			clock-latency-ns = <300000>;
			opp-microvolt-10 = <970000>;
			opp-microvolt-3c = <950000>;
			opp-microvolt-f0 = <930000>;
		};

		/* OR */

		opp00 {
			opp-hz = /bits/ 64 <1000000000>;
			clock-latency-ns = <300000>;
                        opp-microvolt = <970000>, <950000>, <930000>;
		};
        };

And then the platform code needs to tell OPP layer:
"Use OPPs for cut f0 for device X", and OPP layer will store that
somewhere.

And then it will only initialize OPPs after matching this string with
the values.

Out of the earlier two options, I may prefer the first one. As we will
be soon adding support for multiple regulators, and a single regulator
can have min/max/target values.. So, a single list will become too
long.

This would work if we only had a single variable to contend with, but
what I showed you in my previous example is that we have 3 variables
to consider; cut (version), pcode and substrate.

Using the two (simple) examples I provided, how would your suggestion
look in our case?

But, something like this should be generic enough to capture most of
the cases.

@Stephen/Rob ??

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org ? Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog