Device tree binding for DVFS table
Prashant Gaikwad
pgaikwad at nvidia.com
Tue Jul 17 10:22:12 EDT 2012
On Tuesday 17 July 2012 06:50 PM, Mark Brown wrote:
> On Tue, Jul 17, 2012 at 06:07:23PM +0530, Prashant Gaikwad wrote:
>> On Tuesday 17 July 2012 12:06 AM, Turquette, Mike wrote:
>> reg : operating voltage in microvolt
> What happens if there's more than one supply that needs to be varied?
Each rail's dvfs-table will have OPP nodes defined for different
voltages and each OPP node contains frequency for all clocks affecting
that rail.
Just for presentation:
In following example when <&ref 1> clock rate is set to 500000, sm0 need
to operate at 750000000 micrvolt and sm1 at 800000000.
dvfs-rail-1 {
reg_id = <&sm0>;
opp at 750000000 {
frequency-table at 102 {
frequencies = <&osc 0 314000>, <&ref 1 500000>;
};
};
};
dvfs-rail-2 {
reg_id = <&sm1>;
opp at 800000000 {
frequency-table at 102 {
frequencies = <&ref 1 5000000>;
};
};
};
>> tolerance : can be used to calculate required voltage. (optional,
>> can be replaced by other relevant parameter to calculate required
>> voltage)
> What are the semantics of this field?
I used "tolerance" just for example to derive the range of voltage.
May be as done for OMAP,
regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
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