[V4,2/3] OPP: Allow multiple OPP tables to be passed via DT

On some platforms (Like Qualcomm's SoCs), it is not decided until
runtime on what OPPs to use. The OPP tables can be fixed at compile
time, but which table to use is found out only after reading some efuses
(sort of an eeprom) and knowing characteristics of the SoC.

To support such platform we need to pass multiple OPP tables per device
and hardware should be able to choose one and only one table out of
those.

Update OPP-v2 bindings to support that.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 Documentation/devicetree/bindings/power/opp.txt | 5 +++++
 1 file changed, 5 insertions(+)

On 04/30/2015 07:08 AM, Viresh Kumar wrote:
> On some platforms (Like Qualcomm's SoCs), it is not decided until
> runtime on what OPPs to use. The OPP tables can be fixed at compile
> time, but which table to use is found out only after reading some efuses
> (sort of an eeprom) and knowing characteristics of the SoC.

they are more like prom than eeprom in many instances.

> 
> To support such platform we need to pass multiple OPP tables per device
> and hardware should be able to choose one and only one table out of
> those.
> 
> Update OPP-v2 bindings to support that.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  Documentation/devicetree/bindings/power/opp.txt | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/power/opp.txt b/Documentation/devicetree/bindings/power/opp.txt
> index 3b67a5c8d965..07959903ec32 100644
> --- a/Documentation/devicetree/bindings/power/opp.txt
> +++ b/Documentation/devicetree/bindings/power/opp.txt
> @@ -14,6 +14,9 @@ Devices supporting OPPs must set their "operating-points-v2" property with
>  phandle to a OPP descriptor in their DT node. The OPP core will use this phandle
>  to find the operating points for the device.
>  
> +Devices may want to choose OPP tables at runtime and so can provide a list of
> +phandles here. But only *one* of them should be chosen at runtime.
> +
>  
>  * OPP Descriptor Node
>  
> @@ -28,6 +31,8 @@ This describes the OPPs belonging to a device. This node can have following
>    reference an OPP.
>  
>  Optional properties:
> +- opp-name: Name of the OPP table, to uniquely identify it if more than one OPP
> +  table is supplied in "operating-points-v2" property of device.
>  - shared-opp: Indicates that device nodes using this OPP descriptor'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,
> 

With some SoCs like AM335x - thanks to some brain dead incompatible
hardware design choices, this might end up as a big list or various
OPP tables. but overall, I must prefer this approach as well.

Thanks for proposing this. will be great to see examples documented in
bindings doc as well.

With no further issues,
Acked-by: Nishanth Menon <nm@ti.com>

On 12-05-15, 11:09, Nishanth Menon wrote:
> On 04/30/2015 07:08 AM, Viresh Kumar wrote:
> > (sort of an eeprom) and knowing characteristics of the SoC.
> 
> they are more like prom than eeprom in many instances.

Will replace.

> With some SoCs like AM335x - thanks to some brain dead incompatible
> hardware design choices, this might end up as a big list or various
> OPP tables. but overall, I must prefer this approach as well.
> 
> Thanks for proposing this. will be great to see examples documented in
> bindings doc as well.

Right.

On 04/30, Viresh Kumar wrote:
> On some platforms (Like Qualcomm's SoCs), it is not decided until
> runtime on what OPPs to use. The OPP tables can be fixed at compile
> time, but which table to use is found out only after reading some efuses
> (sort of an eeprom) and knowing characteristics of the SoC.
> 
> To support such platform we need to pass multiple OPP tables per device
> and hardware should be able to choose one and only one table out of
> those.
> 
> Update OPP-v2 bindings to support that.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>