74 lines
3.0 KiB
Plaintext
74 lines
3.0 KiB
Plaintext
* Low Power Management Levels
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The application processor in MSM can do a variety of C-States for low power
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management. These C-States are invoked by the CPUIdle framework when the core
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becomes idle. But based on the time available until the next scheduled wakeup,
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the system can do a combination of low power modes of different resources -
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L2, XO, Vdd Dig and Vdd Mem. The combination is captured in the device tree as
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lpm-level. The units for voltage are dependent on the PMIC used on the target
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and are in uV.
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The required nodes for lpm-levels are:
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- compatible: "qcom,lpm-levels"
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- reg: The numeric level id
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- qcom,mode: The sleep mode of the processor, values for the property are:
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"wfi" - Wait for Interrupt
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"ramp_down_and_wfi" - Ramp down and wait for interrupt
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"standalone_pc" - Standalone power collapse
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"pc" - Power Collapse
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"retention" - Retention
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"pc_suspend" - Suspended Power Collapse
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"pc_no_xo_shutdown" - Power Collapse with no XO shutdown
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- qcom,xo: The state of XO clock. Values are "xo_on" and "xo_off"
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- qcom,l2: The state of L2 cache. Values are:
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"l2_cache_pc" - L2 cache in power collapse
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"l2_cache_retenetion" - L2 cache in retention
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"l2_cache_gdhs" - L2 cache in GDHS
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"l2_cache_active" - L2 cache in active mode
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- qcom,vdd-mem-upper-bound: The upper bound value of mem voltage in uV
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- qcom,vdd-mem-lower-bound: The lower bound value of mem voltage in uV
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- qcom,vdd-dig-upper-bound: The upper bound value of dig voltage in uV
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or an RBCPR (Rapid Bridge Core Power Reduction)
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corner voltage.
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- qcom,vdd-dig-lower-bound: The lower bound value of dig voltage in uV
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or an RBCPR (Rapid Bridge Core Power Reduction)
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corner voltage.
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- qcom,latency-us: The latency in handling the interrupt if this level was
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chosen, in uSec
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- qcom,ss-power: The steady state power expelled when the processor is in this
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level in mWatts
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- qcom,energy-overhead: The energy used up in entering and exiting this level
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in mWatts.uSec
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- qcom,time-overhead: The time spent in entering and exiting this level in uS
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Optional properties
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- qcom,irqs-detectable: The field indicates whether the IRQs are detectable by
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the GIC controller when entering a low power mode.
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- qcom,gpio-detectable: The field indicates whether the GPIOs can be detected
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by the GPIO interrupt controller during a given low
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power mode.
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- qcom,use-qtimer: Indicates whether the target uses the synchronized QTimer.
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Example:
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qcom,lpm-levels {
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qcom,use-qtimer;
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qcom,lpm-level@0 {
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reg = <0>;
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qcom,mode = "wfi";
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qcom,xo = "xo_on";
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qcom,l2 = "l2_cache_active";
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qcom,vdd-mem-upper-bound = <1150000>; /* MAX */
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qcom,vdd-mem-lower-bound = <1050000>; /* ACTIVE */
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qcom,vdd-dig-upper-bound = <5>; /* MAX */
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qcom,vdd-dig-lower-bound = <3>; /* ACTIVE */
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qcom,irqs-detectable;
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qcom,gpio-detectable;
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qcom,latency-us = <100>;
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qcom,ss-power = <650>;
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qcom,energy-overhead = <801>;
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qcom,time-overhead = <200>;
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};
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};
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