| Message ID | 20201202172356.10508-2-nicola.mazzucato@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | viresh kumar |
| Headers | show |
| Series | CPUFreq: Add support for opp-sharing cpus | expand |
Subject should rather be: dt-bindings: opp: Allow empty OPP tables On 02-12-20, 17:23, Nicola Mazzucato wrote: > Currently the optional property opp-shared is used within an opp table > to tell that a set of devices share their clock/voltage lines (and the > opp points). > It is therefore possible to use an empty opp table to convey only that > information, useful in situations where the opp points are provided via > other means (hardware. firmware, etc). > > Update the documentation to remark this additional case and provide an > example. > > Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com> > --- > Documentation/devicetree/bindings/opp/opp.txt | 53 +++++++++++++++++++ > 1 file changed, 53 insertions(+) > > diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt > index 9847dfeeffcb..a5f1f993eab9 100644 > --- a/Documentation/devicetree/bindings/opp/opp.txt > +++ b/Documentation/devicetree/bindings/opp/opp.txt > @@ -72,6 +72,9 @@ Optional properties: > switch their DVFS state together, i.e. they share clock/voltage/current lines. > Missing property means devices have independent clock/voltage/current lines, > but they share OPP tables. > + This optional property can be used without any OPP nodes when its only purpose > + is to describe a dependency of clock/voltage/current lines among a set of > + devices. And instead of this, we should rather update "OPP nodes:" section like this: diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt index 9847dfeeffcb..28077ce3a845 100644 --- a/Documentation/devicetree/bindings/opp/opp.txt +++ b/Documentation/devicetree/bindings/opp/opp.txt @@ -63,11 +63,13 @@ This describes the OPPs belonging to a device. This node can have following - compatible: Allow OPPs to express their compatibility. It should be: "operating-points-v2". +Optional properties: - OPP nodes: One or more OPP nodes describing voltage-current-frequency combinations. Their name isn't significant but their phandle can be used to - reference an OPP. + reference an OPP. These are mandatory except for the case where the OPP table + is present only to indicate dependency between devices using the opp-shared + property. -Optional properties: - 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,
Hi Viresh, thanks for your comments. I will update subject and content as you suggested. Regards, Nicola On 12/8/20 4:29 AM, Viresh Kumar wrote: > Subject should rather be: > > dt-bindings: opp: Allow empty OPP tables > > On 02-12-20, 17:23, Nicola Mazzucato wrote: >> Currently the optional property opp-shared is used within an opp table >> to tell that a set of devices share their clock/voltage lines (and the >> opp points). >> It is therefore possible to use an empty opp table to convey only that >> information, useful in situations where the opp points are provided via >> other means (hardware. firmware, etc). >> >> Update the documentation to remark this additional case and provide an >> example. >> >> Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com> >> --- >> Documentation/devicetree/bindings/opp/opp.txt | 53 +++++++++++++++++++ >> 1 file changed, 53 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt >> index 9847dfeeffcb..a5f1f993eab9 100644 >> --- a/Documentation/devicetree/bindings/opp/opp.txt >> +++ b/Documentation/devicetree/bindings/opp/opp.txt >> @@ -72,6 +72,9 @@ Optional properties: >> switch their DVFS state together, i.e. they share clock/voltage/current lines. >> Missing property means devices have independent clock/voltage/current lines, >> but they share OPP tables. >> + This optional property can be used without any OPP nodes when its only purpose >> + is to describe a dependency of clock/voltage/current lines among a set of >> + devices. > > And instead of this, we should rather update "OPP nodes:" section like > this: > > diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt > index 9847dfeeffcb..28077ce3a845 100644 > --- a/Documentation/devicetree/bindings/opp/opp.txt > +++ b/Documentation/devicetree/bindings/opp/opp.txt > @@ -63,11 +63,13 @@ This describes the OPPs belonging to a device. This node can have following > - compatible: Allow OPPs to express their compatibility. It should be: > "operating-points-v2". > > +Optional properties: > - OPP nodes: One or more OPP nodes describing voltage-current-frequency > combinations. Their name isn't significant but their phandle can be used to > - reference an OPP. > + reference an OPP. These are mandatory except for the case where the OPP table > + is present only to indicate dependency between devices using the opp-shared > + property. > > -Optional properties: > - 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, >
diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt index 9847dfeeffcb..a5f1f993eab9 100644 --- a/Documentation/devicetree/bindings/opp/opp.txt +++ b/Documentation/devicetree/bindings/opp/opp.txt @@ -72,6 +72,9 @@ Optional properties: switch their DVFS state together, i.e. they share clock/voltage/current lines. Missing property means devices have independent clock/voltage/current lines, but they share OPP tables. + This optional property can be used without any OPP nodes when its only purpose + is to describe a dependency of clock/voltage/current lines among a set of + devices. - status: Marks the OPP table enabled/disabled. @@ -568,3 +571,53 @@ Example 6: opp-microvolt-<name>, opp-microamp-<name>: }; }; }; + +Example 7: Single cluster Quad-core ARM cortex A53, OPP points from firmware, +distinct clock controls but two sets of clock/voltage/current lines. + +/ { + cpus { + #address-cells = <2>; + #size-cells = <0>; + + cpu@0 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x100>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 0>; + operating-points-v2 = <&cpu_opp0_table>; + }; + cpu@1 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x101>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 1>; + operating-points-v2 = <&cpu_opp0_table>; + }; + cpu@2 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x102>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 2>; + operating-points-v2 = <&cpu_opp1_table>; + }; + cpu@3 { + compatible = "arm,cortex-a53"; + reg = <0x0 0x103>; + next-level-cache = <&A53_L2>; + clocks = <&dvfs_controller 3>; + operating-points-v2 = <&cpu_opp1_table>; + }; + + }; + + cpu_opp0_table: opp0_table { + compatible = "operating-points-v2"; + opp-shared; + }; + + cpu_opp1_table: opp1_table { + compatible = "operating-points-v2"; + opp-shared; + }; +};
Currently the optional property opp-shared is used within an opp table to tell that a set of devices share their clock/voltage lines (and the opp points). It is therefore possible to use an empty opp table to convey only that information, useful in situations where the opp points are provided via other means (hardware. firmware, etc). Update the documentation to remark this additional case and provide an example. Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com> --- Documentation/devicetree/bindings/opp/opp.txt | 53 +++++++++++++++++++ 1 file changed, 53 insertions(+)