在 2016/8/19 21:36, Rob Herring 写道:

On Tue, Aug 16, 2016 at 10:38:59AM +0800, Finlye Xiao wrote:

quoted

From: Finley Xiao <redacted>

This patch supports adjusting opp's voltage according to leakage

Signed-off-by: Finley Xiao <redacted>
---
  .../devicetree/bindings/power/rockchip-cpu-avs.txt |  37 +++
  drivers/power/avs/Kconfig                          |   8 +
  drivers/power/avs/Makefile                         |   1 +
  drivers/power/avs/rockchip-cpu-avs.c               | 314 +++++++++++++++++++++
  4 files changed, 360 insertions(+)
  create mode 100644 Documentation/devicetree/bindings/power/rockchip-cpu-avs.txt
  create mode 100644 drivers/power/avs/rockchip-cpu-avs.c

diff --git a/Documentation/devicetree/bindings/power/rockchip-cpu-avs.txt b/Documentation/devicetree/bindings/power/rockchip-cpu-avs.txt
new file mode 100644
index 0000000..90f6b08
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/rockchip-cpu-avs.txt

@@ -0,0 +1,37 @@
+Rockchip cpu avs device tree bindings
+-------------------------------------
+
+Under the same frequency, the operating voltage tends to decrease with
+increasing leakage. so it is necessary to adjust opp's voltage according
+to leakage for power.
+
+
+Required properties:
+- compatible: Should be one of the following.
+  - "rockchip,rk3399-cpu-avs" - for RK3399 SoCs.
+- leakage-volt-<name>: Named leakage-volt property. At runtime, the
+  platform can find a cpu's cluster_id according to it's cpu_id and match
+  leakage-volt-<name> property. The property is an array of 3-tuples
+  items, and each item consists of leakage and voltage like
+  <min-leakage-mA max-leakage-mA vol-uV>.
+	min-leakage: minimum leakage in mA.
+	max-leakage: maximum leakage in mA.
+	vol: voltage in microvolt.

How do you determine these values? When do they vary?

How do you determine these values?

run antutu-benchmark
leakage     freq 	min_volt
30mA 	    1608MHz 	1025mV
40mA 	    1608MHz 	1000mV
50mA 	    1608MHz 	975mV

 From the table, we see the min_volt decrease with increasing leakage.
So we can set the default opp-microvolt 1025mV for 1608MHz,
and add an leakage_volt_cluster0 property as follows.
leakage_volt_cluster0 = <
		/*  min(mA)   max(mA)    volt(uV)*/
		    0         40        0
		    41        50        (-25000)
		    51        254       (-50000)

;

If the leakage is between 41mA and 50mA，the opp-microvolt will subtract 25mV。
If the leakage is between 41mA and 50mA，the opp-microvolt will subtract 50mV。
  
When do they vary?

 From the code,
cpufreq_online
--cpufreq_driver->init(policy);  /* add new opp table */
--blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_START, policy);
--cpufreq_init_policy
----cpufreq_set_policy
--------__cpufreq_governor(policy, CPUFREQ_GOV_START);

The cpu's opp table is added in the init function(cpufreq_init)，and I will
register a cpufreq notifier, once the first cpu of cluster is onlined,
my notifer will be called, and if the event is CPUFREQ_START，it will modify
the opp-microvolt according to leakage_volt_cluster0.

quoted

+
+Example:
+
+	cpu_avs: cpu-avs {
+		compatible = "rockchip,rk3399-cpu-avs";

This isn't really a hardware block. For the same reasons we don't have
cpufreq nodes. So I don't think this belongs in DT.

if I delete the compatible property like the thermal-zones node, is it allowed?
cpu_avs: cpu-avs {
	leakage_volt_cluster0 = <
		/*  min(mA)   max(mA)    volt(uV)*/
		    0         40        0
		    41        50        (-25000)
		    51        254       (-50000)
	>;
	leakage_volt_cluster1 = <
		/*  min(mA)   max(mA)    volt(uV)*/
		    0         40        0
		    41        50        (-25000)
		    51        254       (-50000)
	>;
}

Rob

-- 
Finley


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