nxp,imx9-pstate

Description

NXP i.MX9 performance state (P-state) for the Cortex-A application cores.

This binding is shared by the i.MX9 family (i.MX91, i.MX93, i.MX95, i.MX943
and derivatives). Each P-state selects a core clock frequency that the SoC
P-state driver applies when the state is entered. The set of usable
frequencies is SoC specific: only the frequencies the SoC driver implements
may be requested, and any other value is rejected at build time.

A SoC driver may change the core clock alone and leave the supply voltage at
the level set by the boot loader. Where that is the case, all frequencies
listed in devicetree must be usable at that voltage. Where the cores of a
cluster share the clock source, a P-state applies to the whole cluster and the
SoC driver requires an SMP build.

Example configuration:

performance-states {
        pstate_0: pstate-0 {
                compatible = "nxp,imx9-pstate";
                load-threshold = <60>;
                clock-frequency = <DT_FREQ_M(1692)>;
        };
        pstate_1: pstate-1 {
                compatible = "nxp,imx9-pstate";
                load-threshold = <0>;
                clock-frequency = <DT_FREQ_M(900)>;
        };
};

Properties

Properties not inherited from the base binding file.

Name

Type

Details

load-threshold

int

CPU load threshold, in percent, for entering this performance state. Once
the CPU load exceeds this threshold, it becomes a valid performance state
for the P-state driver to switch to.

This property is required.

clock-frequency

int

Core clock frequency, in Hz, applied when this performance state is
selected. The accepted values are defined by the SoC P-state driver.

This property is required.