On 31-07-15, 09:37, Stephen Boyd wrote:

quoted

For qcom platforms, the frequency is almost always constant.
There may be some tables where we have a couple higher
frequencies than others because the speed bin is different.
Otherwise the voltage/current is changing based on the silicon
characteristics. So the biggest duplication is the frequency
property.

As far as I know there isn't any algorithm to generate the
voltage values. It's all hand tuned tables based on the silicon
characterization, so we're left to store these tables in DT and
pick the right one at runtime. With regards to the table
explosion, on qcom platforms we haven't worried that we have ~40
tables, but I'm not opposed to expressing it in a smaller set of
nodes, tables, etc. if that's what's desired.

Do we need vendor specific properties for that though? Or do we
need some sort of extended frequency/voltage properties that are
arrays of values that we can index into based on some silicon
characteristics? I like the name based approach because it's
simple. Use this OPP table because it's called
x-y-z-characteristics and be done. Cramming the tables into less
lines may save us some typing and dtb space, but I'm not sure
what else it does.

What about something like this:

diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
index 0cb44dc21f97..bad7a8299b9c 100644
--- a/Documentation/devicetree/bindings/opp/opp.txt
+++ b/Documentation/devicetree/bindings/opp/opp.txt

@@ -74,6 +74,8 @@ This describes the OPPs belonging to a device. This node can have following
   reference an OPP.
 
 Optional properties:
+- opp-cuts: One or more strings, describing the versions of hardware the OPPs
+  can support.

 - opp-shared: Indicates that device nodes using this OPP Table Node's phandle
   switch their DVFS state together, i.e. they share clock/voltage/current lines.
   Missing property means devices have independent clock/voltage/current lines,

@@ -100,6 +102,9 @@ properties.
   Entries for multiple regulators must be present in the same order as
   regulators are specified in device's DT node.
 
+  If used with 'opp-cuts', then the number of entries present here must match
+  the number of strings present in 'opp-cuts'.
+
 - opp-microamp: The maximum current drawn by the device in microamperes
   considering system specific parameters (such as transients, process, aging,
   maximum operating temperature range etc.) as necessary. This may be used to