Message ID | 20211011165707.138157-4-marcan@marcan.st |
---|---|
State | Changes Requested, archived |
Headers | show |
Series | Apple SoC CPU P-state switching | expand |
Context | Check | Description |
---|---|---|
robh/checkpatch | success | |
robh/dt-meta-schema | success | |
robh/dtbs-check | success |
On 11/10/2021 18:57, Hector Martin wrote: > This device represents the CPU performance state switching mechanism as > a clock controller, to be used with the standard cpufreq-dt > infrastructure. > > Signed-off-by: Hector Martin <marcan@marcan.st> > --- > .../bindings/clock/apple,cluster-clk.yaml | 115 ++++++++++++++++++ > 1 file changed, 115 insertions(+) > create mode 100644 Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml > > diff --git a/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml b/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml > new file mode 100644 > index 000000000000..9a8b863dadc0 > --- /dev/null > +++ b/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml > @@ -0,0 +1,115 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/clock/apple,cluster-clk.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: CPU cluster frequency scaling for Apple SoCs > + > +maintainers: > + - Hector Martin <marcan@marcan.st> > + > +description: | > + Apple SoCs control CPU cluster frequencies by using a performance state > + index. This node represents the feature as a clock controller, and uses > + a reference to the CPU OPP table to translate clock frequencies into > + performance states. This allows the CPUs to use the standard cpufreq-dt > + mechanism for frequency scaling. > + > +properties: > + compatible: > + items: > + - enum: > + - apple,t8103-cluster-clk > + - const: apple,cluster-clk > + > + reg: > + maxItems: 1 > + > + '#clock-cells': > + const: 0 > + > + operating-points-v2: > + $ref: /schemas/types.yaml#/definitions/phandle-array > + description: > + A reference to the OPP table used for the CPU cluster controlled by this > + device instance. The table should contain an `opp-level` property for > + every OPP, which represents the p-state index used by the hardware to > + represent this performance level. > + > + OPPs may also have a `required-opps` property (see power-domains). > + > + power-domains: > + maxItems: 1 > + description: > + An optional reference to a power domain provider that links its > + performance state to the CPU cluster performance state. This is typically > + a memory controller. If set, the `required-opps` property in the CPU > + frequency OPP nodes will be used to change the performance state of this > + provider state in tandem with CPU frequency changes. > + > +required: > + - compatible > + - reg > + - '#clock-cells' > + - operating-points-v2 > + > +additionalProperties: false > + > + One line break. > +examples: > + - | > + pcluster_opp: opp-table-1 { > + compatible = "operating-points-v2"; > + opp-shared; > + > + opp01 { > + opp-hz = /bits/ 64 <600000000>; > + opp-microvolt = <781000>; > + opp-level = <1>; > + clock-latency-ns = <8000>; > + required-opps = <&mcc_lowperf>; > + }; > + /* intermediate p-states omitted */ > + opp15 { > + opp-hz = /bits/ 64 <3204000000>; > + opp-microvolt = <1081000>; > + opp-level = <15>; > + clock-latency-ns = <56000>; > + required-opps = <&mcc_highperf>; > + }; > + }; > + > + mcc_opp: opp-table-2 { > + compatible = "operating-points-v2"; Wrong compatible. > + > + mcc_lowperf: opp0 { > + opp-level = <0>; > + apple,memory-perf-config = <0x813057f 0x1800180>; > + }; > + mcc_highperf: opp1 { > + opp-level = <1>; > + apple,memory-perf-config = <0x133 0x55555340>; > + }; > + }; > + > + soc { > + #address-cells = <2>; > + #size-cells = <2>; > + > + mcc: memory-controller@200200000 { > + compatible = "apple,t8103-mcc", "apple,mcc"; > + #power-domain-cells = <0>; > + reg = <0x2 0x200000 0x0 0x200000>; > + operating-points-v2 = <&mcc_opp>; > + apple,num-channels = <8>; > + }; > + > + clk_pcluster: clock-controller@211e20000 { > + compatible = "apple,t8103-cluster-clk", "apple,cluster-clk"; > + #clock-cells = <0>; > + reg = <0x2 0x11e20000 0x0 0x4000>; > + operating-points-v2 = <&pcluster_opp>; > + power-domains = <&mcc>; > + }; > + }; > Best regards, Krzysztof
Apart from what Krzysztof already said: On 12-10-21, 10:51, Krzysztof Kozlowski wrote: > On 11/10/2021 18:57, Hector Martin wrote: > > + pcluster_opp: opp-table-1 { > > + compatible = "operating-points-v2"; > > + opp-shared; > > + > > + opp01 { > > + opp-hz = /bits/ 64 <600000000>; > > + opp-microvolt = <781000>; > > + opp-level = <1>; The opp-level thing wasn't designed to work this way, though it may work just fine. It was designed as a unique key for power-domains, which don't have opp-hz. The OPP core currently looks at 3 different values, which can act as a unique key to identify the OPP. clk-rate, bandwidth and level. I think this is the first platform which has both hz and level in the CPUs OPP table. What exactly is level in this case ? Again, it may work fine, I just don't know where it may end up breaking :)
On 12/10/2021 18.57, Viresh Kumar wrote: > I didn't realize earlier that we have moved out of lists :) Whoops, sorry, I was on mobile and must've hit the wrong reply button! My apologies. > On 12-10-21, 18:54, Hector Martin "marcan" wrote: >> Typically cpufreq-dt is used with clock drivers that directly take >> the clock frequency and do whatever voodoo is necessary to set it >> for the CPU. But here, the hardware just wants to know the index, >> and does everything itself. So we need to encode that somewhere, to >> avoid hardcoding it in the clock driver. >> >> In general, based on how these SoCs are designed, we're trying to >> avoid having tables of volatile information in the drivers, and >> instead keep everything in the DT. This means we have a good chance >> that these drivers will continue to work with future SoC >> generations, since Apple doesn't change register definitions >> randomly most of the time. > > Yeah I get that and it is actually better this way. I just wanted to > point out that we didn't think of it this way earlier :) Yeah, makes sense. Seems to work fine :)
diff --git a/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml b/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml new file mode 100644 index 000000000000..9a8b863dadc0 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml @@ -0,0 +1,115 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/clock/apple,cluster-clk.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: CPU cluster frequency scaling for Apple SoCs + +maintainers: + - Hector Martin <marcan@marcan.st> + +description: | + Apple SoCs control CPU cluster frequencies by using a performance state + index. This node represents the feature as a clock controller, and uses + a reference to the CPU OPP table to translate clock frequencies into + performance states. This allows the CPUs to use the standard cpufreq-dt + mechanism for frequency scaling. + +properties: + compatible: + items: + - enum: + - apple,t8103-cluster-clk + - const: apple,cluster-clk + + reg: + maxItems: 1 + + '#clock-cells': + const: 0 + + operating-points-v2: + $ref: /schemas/types.yaml#/definitions/phandle-array + description: + A reference to the OPP table used for the CPU cluster controlled by this + device instance. The table should contain an `opp-level` property for + every OPP, which represents the p-state index used by the hardware to + represent this performance level. + + OPPs may also have a `required-opps` property (see power-domains). + + power-domains: + maxItems: 1 + description: + An optional reference to a power domain provider that links its + performance state to the CPU cluster performance state. This is typically + a memory controller. If set, the `required-opps` property in the CPU + frequency OPP nodes will be used to change the performance state of this + provider state in tandem with CPU frequency changes. + +required: + - compatible + - reg + - '#clock-cells' + - operating-points-v2 + +additionalProperties: false + + +examples: + - | + pcluster_opp: opp-table-1 { + compatible = "operating-points-v2"; + opp-shared; + + opp01 { + opp-hz = /bits/ 64 <600000000>; + opp-microvolt = <781000>; + opp-level = <1>; + clock-latency-ns = <8000>; + required-opps = <&mcc_lowperf>; + }; + /* intermediate p-states omitted */ + opp15 { + opp-hz = /bits/ 64 <3204000000>; + opp-microvolt = <1081000>; + opp-level = <15>; + clock-latency-ns = <56000>; + required-opps = <&mcc_highperf>; + }; + }; + + mcc_opp: opp-table-2 { + compatible = "operating-points-v2"; + + mcc_lowperf: opp0 { + opp-level = <0>; + apple,memory-perf-config = <0x813057f 0x1800180>; + }; + mcc_highperf: opp1 { + opp-level = <1>; + apple,memory-perf-config = <0x133 0x55555340>; + }; + }; + + soc { + #address-cells = <2>; + #size-cells = <2>; + + mcc: memory-controller@200200000 { + compatible = "apple,t8103-mcc", "apple,mcc"; + #power-domain-cells = <0>; + reg = <0x2 0x200000 0x0 0x200000>; + operating-points-v2 = <&mcc_opp>; + apple,num-channels = <8>; + }; + + clk_pcluster: clock-controller@211e20000 { + compatible = "apple,t8103-cluster-clk", "apple,cluster-clk"; + #clock-cells = <0>; + reg = <0x2 0x11e20000 0x0 0x4000>; + operating-points-v2 = <&pcluster_opp>; + power-domains = <&mcc>; + }; + };
This device represents the CPU performance state switching mechanism as a clock controller, to be used with the standard cpufreq-dt infrastructure. Signed-off-by: Hector Martin <marcan@marcan.st> --- .../bindings/clock/apple,cluster-clk.yaml | 115 ++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/apple,cluster-clk.yaml