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Commit 0b221d83 authored by Pavankumar Kondeti's avatar Pavankumar Kondeti
Browse files

arm64: topology: Allow specifying the CPU efficiency from device tree 



The efficiency of a CPU can vary across SoCs depending on the cache size,
bus interconnect frequencies etc. Allow specifying this from the device
tree. This value overrides the default values hardcoded in the efficiency
table.

CRs-Fixed: 1003878
Change-Id: Ie9ba69e11317e6eb6462630226355747d1def646
Signed-off-by: default avatarPavankumar Kondeti <pkondeti@codeaurora.org>
parent cdd5967f

Documentation/devicetree/bindings/arm/cpus.txt

+14 −0
Original line number Diff line number Diff line
@@ -210,6 +210,20 @@ nodes to be present and contain the properties described below. 
			  property identifying a 64-bit zero-initialised

			  memory location.



	- efficiency

		Usage: optional.

		Value type: <u32>

		Definition:

			# Specifies the CPU efficiency. The CPU efficiency is

			a unit less number and it is intended to show relative

			performance of CPUs when normalized for clock frequency

			(instructions per cycle performance).



			The efficiency of a CPU can vary across SoCs depending

			on the cache size, bus interconnect frequencies etc.

			This value overrides the default efficiency value

			defined for the corresponding CPU architecture.



	- qcom,saw

		Usage: required for systems that have an "enable-method"

		       property value of "qcom,kpss-acc-v1" or

arch/arm64/kernel/topology.c

+22 −8
Original line number Diff line number Diff line
@@ -280,6 +280,7 @@ static void __init parse_dt_cpu_power(void) 
	for_each_possible_cpu(cpu) {

		const u32 *rate;

		int len;

		u32 efficiency;



		/* Too early to use cpu->of_node */

		cn = of_get_cpu_node(cpu, NULL);
@@ -288,16 +289,29 @@ static void __init parse_dt_cpu_power(void) 
			continue;

		}



		for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++)

			if (of_device_is_compatible(cn, cpu_eff->compatible))

		/*

		 * The CPU efficiency value passed from the device tree

		 * overrides the value defined in the table_efficiency[]

		 */

		if (of_property_read_u32(cn, "efficiency", &efficiency) < 0) {



			for (cpu_eff = table_efficiency;

					cpu_eff->compatible; cpu_eff++)



				if (of_device_is_compatible(cn,

						cpu_eff->compatible))

					break;



			if (cpu_eff->compatible == NULL) {

			pr_warn("%s: Unknown CPU type\n", cn->full_name);

				pr_warn("%s: Unknown CPU type\n",

						cn->full_name);

				continue;

			}



		per_cpu(cpu_efficiency, cpu) = cpu_eff->efficiency;

			efficiency = cpu_eff->efficiency;

		}



		per_cpu(cpu_efficiency, cpu) = efficiency;



		rate = of_get_property(cn, "clock-frequency", &len);

		if (!rate || len != 4) {
@@ -306,7 +320,7 @@ static void __init parse_dt_cpu_power(void) 
			continue;

		}



		capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;

		capacity = ((be32_to_cpup(rate)) >> 20) * efficiency;



		/* Save min capacity of the system */

		if (capacity < min_capacity)