diff options
Diffstat (limited to 'dts/Bindings/arm/cpu-capacity.txt')
| -rw-r--r-- | dts/Bindings/arm/cpu-capacity.txt | 238 |
1 files changed, 0 insertions, 238 deletions
diff --git a/dts/Bindings/arm/cpu-capacity.txt b/dts/Bindings/arm/cpu-capacity.txt deleted file mode 100644 index 380e21c5fc..0000000000 --- a/dts/Bindings/arm/cpu-capacity.txt +++ /dev/null @@ -1,238 +0,0 @@ -========================================== -ARM CPUs capacity bindings -========================================== - -========================================== -1 - Introduction -========================================== - -ARM systems may be configured to have cpus with different power/performance -characteristics within the same chip. In this case, additional information has -to be made available to the kernel for it to be aware of such differences and -take decisions accordingly. - -========================================== -2 - CPU capacity definition -========================================== - -CPU capacity is a number that provides the scheduler information about CPUs -heterogeneity. Such heterogeneity can come from micro-architectural differences -(e.g., ARM big.LITTLE systems) or maximum frequency at which CPUs can run -(e.g., SMP systems with multiple frequency domains). Heterogeneity in this -context is about differing performance characteristics; this binding tries to -capture a first-order approximation of the relative performance of CPUs. - -CPU capacities are obtained by running a suitable benchmark. This binding makes -no guarantees on the validity or suitability of any particular benchmark, the -final capacity should, however, be: - -* A "single-threaded" or CPU affine benchmark -* Divided by the running frequency of the CPU executing the benchmark -* Not subject to dynamic frequency scaling of the CPU - -For the time being we however advise usage of the Dhrystone benchmark. What -above thus becomes: - -CPU capacities are obtained by running the Dhrystone benchmark on each CPU at -max frequency (with caches enabled). The obtained DMIPS score is then divided -by the frequency (in MHz) at which the benchmark has been run, so that -DMIPS/MHz are obtained. Such values are then normalized w.r.t. the highest -score obtained in the system. - -========================================== -3 - capacity-dmips-mhz -========================================== - -capacity-dmips-mhz is an optional cpu node [1] property: u32 value -representing CPU capacity expressed in normalized DMIPS/MHz. At boot time, the -maximum frequency available to the cpu is then used to calculate the capacity -value internally used by the kernel. - -capacity-dmips-mhz property is all-or-nothing: if it is specified for a cpu -node, it has to be specified for every other cpu nodes, or the system will -fall back to the default capacity value for every CPU. If cpufreq is not -available, final capacities are calculated by directly using capacity-dmips- -mhz values (normalized w.r.t. the highest value found while parsing the DT). - -=========================================== -4 - Examples -=========================================== - -Example 1 (ARM 64-bit, 6-cpu system, two clusters): -The capacities-dmips-mhz or DMIPS/MHz values (scaled to 1024) -are 1024 and 578 for cluster0 and cluster1. Further normalization -is done by the operating system based on cluster0@max-freq=1100 and -custer1@max-freq=850, final capacities are 1024 for cluster0 and -446 for cluster1 (576*850/1100). - -cpus { - #address-cells = <2>; - #size-cells = <0>; - - cpu-map { - cluster0 { - core0 { - cpu = <&A57_0>; - }; - core1 { - cpu = <&A57_1>; - }; - }; - - cluster1 { - core0 { - cpu = <&A53_0>; - }; - core1 { - cpu = <&A53_1>; - }; - core2 { - cpu = <&A53_2>; - }; - core3 { - cpu = <&A53_3>; - }; - }; - }; - - idle-states { - entry-method = "psci"; - - CPU_SLEEP_0: cpu-sleep-0 { - compatible = "arm,idle-state"; - arm,psci-suspend-param = <0x0010000>; - local-timer-stop; - entry-latency-us = <100>; - exit-latency-us = <250>; - min-residency-us = <150>; - }; - - CLUSTER_SLEEP_0: cluster-sleep-0 { - compatible = "arm,idle-state"; - arm,psci-suspend-param = <0x1010000>; - local-timer-stop; - entry-latency-us = <800>; - exit-latency-us = <700>; - min-residency-us = <2500>; - }; - }; - - A57_0: cpu@0 { - compatible = "arm,cortex-a57"; - reg = <0x0 0x0>; - device_type = "cpu"; - enable-method = "psci"; - next-level-cache = <&A57_L2>; - clocks = <&scpi_dvfs 0>; - cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; - capacity-dmips-mhz = <1024>; - }; - - A57_1: cpu@1 { - compatible = "arm,cortex-a57"; - reg = <0x0 0x1>; - device_type = "cpu"; - enable-method = "psci"; - next-level-cache = <&A57_L2>; - clocks = <&scpi_dvfs 0>; - cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; - capacity-dmips-mhz = <1024>; - }; - - A53_0: cpu@100 { - compatible = "arm,cortex-a53"; - reg = <0x0 0x100>; - device_type = "cpu"; - enable-method = "psci"; - next-level-cache = <&A53_L2>; - clocks = <&scpi_dvfs 1>; - cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; - capacity-dmips-mhz = <578>; - }; - - A53_1: cpu@101 { - compatible = "arm,cortex-a53"; - reg = <0x0 0x101>; - device_type = "cpu"; - enable-method = "psci"; - next-level-cache = <&A53_L2>; - clocks = <&scpi_dvfs 1>; - cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; - capacity-dmips-mhz = <578>; - }; - - A53_2: cpu@102 { - compatible = "arm,cortex-a53"; - reg = <0x0 0x102>; - device_type = "cpu"; - enable-method = "psci"; - next-level-cache = <&A53_L2>; - clocks = <&scpi_dvfs 1>; - cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; - capacity-dmips-mhz = <578>; - }; - - A53_3: cpu@103 { - compatible = "arm,cortex-a53"; - reg = <0x0 0x103>; - device_type = "cpu"; - enable-method = "psci"; - next-level-cache = <&A53_L2>; - clocks = <&scpi_dvfs 1>; - cpu-idle-states = <&CPU_SLEEP_0 &CLUSTER_SLEEP_0>; - capacity-dmips-mhz = <578>; - }; - - A57_L2: l2-cache0 { - compatible = "cache"; - }; - - A53_L2: l2-cache1 { - compatible = "cache"; - }; -}; - -Example 2 (ARM 32-bit, 4-cpu system, two clusters, - cpus 0,1@1GHz, cpus 2,3@500MHz): -capacities-dmips-mhz are scaled w.r.t. 2 (cpu@0 and cpu@1), this means that first -cpu@0 and cpu@1 are twice fast than cpu@2 and cpu@3 (at the same frequency) - -cpus { - #address-cells = <1>; - #size-cells = <0>; - - cpu0: cpu@0 { - device_type = "cpu"; - compatible = "arm,cortex-a15"; - reg = <0>; - capacity-dmips-mhz = <2>; - }; - - cpu1: cpu@1 { - device_type = "cpu"; - compatible = "arm,cortex-a15"; - reg = <1>; - capacity-dmips-mhz = <2>; - }; - - cpu2: cpu@2 { - device_type = "cpu"; - compatible = "arm,cortex-a15"; - reg = <0x100>; - capacity-dmips-mhz = <1>; - }; - - cpu3: cpu@3 { - device_type = "cpu"; - compatible = "arm,cortex-a15"; - reg = <0x101>; - capacity-dmips-mhz = <1>; - }; -}; - -=========================================== -5 - References -=========================================== - -[1] ARM Linux Kernel documentation - CPUs bindings - Documentation/devicetree/bindings/arm/cpus.yaml |