Merge Qualcomm specific idle-state binding with generic one.
Signed-off-by: David Heidelberg <[email protected]>
---
v3:
- integrate into idle-state.yml
- orig. patch name was:
"[v2] dt-bindings: arm/msm/qcom,idle-state convert to YAML"
Signed-off-by: David Heidelberg <[email protected]>
---
.../devicetree/bindings/arm/idle-states.yaml | 107 ++++++++++++++++++
.../bindings/arm/msm/qcom,idle-state.txt | 84 --------------
2 files changed, 107 insertions(+), 84 deletions(-)
delete mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
diff --git a/Documentation/devicetree/bindings/arm/idle-states.yaml b/Documentation/devicetree/bindings/arm/idle-states.yaml
index 52bce5dbb11f..fde1557f2332 100644
--- a/Documentation/devicetree/bindings/arm/idle-states.yaml
+++ b/Documentation/devicetree/bindings/arm/idle-states.yaml
@@ -241,6 +241,64 @@ description: |+
[6] ARM Linux Kernel documentation - Booting AArch64 Linux
Documentation/arm64/booting.rst
+ ===========================================
+ 5 - Qualcomm specific STATES
+ ===========================================
+
+ cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle
+ states. Idle states have different enter/exit latency and residency values.
+ The idle states supported by the QCOM SoC are defined as -
+
+ * Standby
+ * Retention
+ * Standalone Power Collapse (Standalone PC or SPC)
+ * Power Collapse (PC)
+
+ Standby: Standby does a little more in addition to architectural clock gating.
+ When the WFI instruction is executed the ARM core would gate its internal
+ clocks. In addition to gating the clocks, QCOM cpus use this instruction as a
+ trigger to execute the SPM state machine. The SPM state machine waits for the
+ interrupt to trigger the core back in to active. This triggers the cache
+ hierarchy to enter standby states, when all cpus are idle. An interrupt brings
+ the SPM state machine out of its wait, the next step is to ensure that the
+ cache hierarchy is also out of standby, and then the cpu is allowed to resume
+ execution. This state is defined as a generic ARM WFI state by the ARM cpuidle
+ driver and is not defined in the DT. The SPM state machine should be
+ configured to execute this state by default and after executing every other
+ state below.
+
+ Retention: Retention is a low power state where the core is clock gated and
+ the memory and the registers associated with the core are retained. The
+ voltage may be reduced to the minimum value needed to keep the processor
+ registers active. The SPM should be configured to execute the retention
+ sequence and would wait for interrupt, before restoring the cpu to execution
+ state. Retention may have a slightly higher latency than Standby.
+
+ Standalone PC: A cpu can power down and warmboot if there is a sufficient time
+ between the time it enters idle and the next known wake up. SPC mode is used
+ to indicate a core entering a power down state without consulting any other
+ cpu or the system resources. This helps save power only on that core. The SPM
+ sequence for this idle state is programmed to power down the supply to the
+ core, wait for the interrupt, restore power to the core, and ensure the
+ system state including cache hierarchy is ready before allowing core to
+ resume. Applying power and resetting the core causes the core to warmboot
+ back into Elevation Level (EL) which trampolines the control back to the
+ kernel. Entering a power down state for the cpu, needs to be done by trapping
+ into a EL. Failing to do so, would result in a crash enforced by the warm boot
+ code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to
+ be flushed in s/w, before powering down the core.
+
+ Power Collapse: This state is similar to the SPC mode, but distinguishes
+ itself in that the cpu acknowledges and permits the SoC to enter deeper sleep
+ modes. In a hierarchical power domain SoC, this means L2 and other caches can
+ be flushed, system bus, clocks - lowered, and SoC main XO clock gated and
+ voltages reduced, provided all cpus enter this state. Since the span of low
+ power modes possible at this state is vast, the exit latency and the residency
+ of this low power mode would be considered high even though at a cpu level,
+ this essentially is cpu power down. The SPM in this state also may handshake
+ with the Resource power manager (RPM) processor in the SoC to indicate a
+ complete application processor subsystem shut down.
+
properties:
$nodename:
const: idle-states
@@ -323,6 +381,44 @@ patternProperties:
- exit-latency-us
- min-residency-us
+ "^(ret|spc|pc)$":
+ type: object
+ description:
+ Each state node represents a domain idle state description.
+
+ properties:
+ compatible:
+ items:
+ - enum:
+ - qcom,idle-state-ret
+ - qcom,idle-state-spc
+ - qcom,idle-state-pc
+ - const: arm,idle-state
+
+ entry-latency-us:
+ description:
+ The worst case latency in microseconds required to enter the idle
+ state. Note that, the exit-latency-us duration may be guaranteed only
+ after the entry-latency-us has passed.
+
+ exit-latency-us:
+ description:
+ The worst case latency in microseconds required to exit the idle
+ state.
+
+ min-residency-us:
+ description:
+ The minimum residency duration in microseconds after which the idle
+ state will yield power benefits, after overcoming the overhead while
+ entering the idle state.
+
+ required:
+ - compatible
+ - entry-latency-us
+ - exit-latency-us
+ - min-residency-us
+
+
additionalProperties: false
examples:
@@ -658,4 +754,15 @@ examples:
};
};
+ - |
+ // Example 3 - QCOM SPC
+ idle-states {
+ cpu_spc: spc {
+ compatible = "qcom,idle-state-spc", "arm,idle-state";
+ entry-latency-us = <150>;
+ exit-latency-us = <200>;
+ min-residency-us = <2000>;
+ };
+ };
+
...
diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
deleted file mode 100644
index 6ce0b212ec6d..000000000000
--- a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
+++ /dev/null
@@ -1,84 +0,0 @@
-QCOM Idle States for cpuidle driver
-
-ARM provides idle-state node to define the cpuidle states, as defined in [1].
-cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle
-states. Idle states have different enter/exit latency and residency values.
-The idle states supported by the QCOM SoC are defined as -
-
- * Standby
- * Retention
- * Standalone Power Collapse (Standalone PC or SPC)
- * Power Collapse (PC)
-
-Standby: Standby does a little more in addition to architectural clock gating.
-When the WFI instruction is executed the ARM core would gate its internal
-clocks. In addition to gating the clocks, QCOM cpus use this instruction as a
-trigger to execute the SPM state machine. The SPM state machine waits for the
-interrupt to trigger the core back in to active. This triggers the cache
-hierarchy to enter standby states, when all cpus are idle. An interrupt brings
-the SPM state machine out of its wait, the next step is to ensure that the
-cache hierarchy is also out of standby, and then the cpu is allowed to resume
-execution. This state is defined as a generic ARM WFI state by the ARM cpuidle
-driver and is not defined in the DT. The SPM state machine should be
-configured to execute this state by default and after executing every other
-state below.
-
-Retention: Retention is a low power state where the core is clock gated and
-the memory and the registers associated with the core are retained. The
-voltage may be reduced to the minimum value needed to keep the processor
-registers active. The SPM should be configured to execute the retention
-sequence and would wait for interrupt, before restoring the cpu to execution
-state. Retention may have a slightly higher latency than Standby.
-
-Standalone PC: A cpu can power down and warmboot if there is a sufficient time
-between the time it enters idle and the next known wake up. SPC mode is used
-to indicate a core entering a power down state without consulting any other
-cpu or the system resources. This helps save power only on that core. The SPM
-sequence for this idle state is programmed to power down the supply to the
-core, wait for the interrupt, restore power to the core, and ensure the
-system state including cache hierarchy is ready before allowing core to
-resume. Applying power and resetting the core causes the core to warmboot
-back into Elevation Level (EL) which trampolines the control back to the
-kernel. Entering a power down state for the cpu, needs to be done by trapping
-into a EL. Failing to do so, would result in a crash enforced by the warm boot
-code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to
-be flushed in s/w, before powering down the core.
-
-Power Collapse: This state is similar to the SPC mode, but distinguishes
-itself in that the cpu acknowledges and permits the SoC to enter deeper sleep
-modes. In a hierarchical power domain SoC, this means L2 and other caches can
-be flushed, system bus, clocks - lowered, and SoC main XO clock gated and
-voltages reduced, provided all cpus enter this state. Since the span of low
-power modes possible at this state is vast, the exit latency and the residency
-of this low power mode would be considered high even though at a cpu level,
-this essentially is cpu power down. The SPM in this state also may handshake
-with the Resource power manager (RPM) processor in the SoC to indicate a
-complete application processor subsystem shut down.
-
-The idle-state for QCOM SoCs are distinguished by the compatible property of
-the idle-states device node.
-
-The devicetree representation of the idle state should be -
-
-Required properties:
-
-- compatible: Must be one of -
- "qcom,idle-state-ret",
- "qcom,idle-state-spc",
- "qcom,idle-state-pc",
- and "arm,idle-state".
-
-Other required and optional properties are specified in [1].
-
-Example:
-
- idle-states {
- CPU_SPC: spc {
- compatible = "qcom,idle-state-spc", "arm,idle-state";
- entry-latency-us = <150>;
- exit-latency-us = <200>;
- min-residency-us = <2000>;
- };
- };
-
-[1]. Documentation/devicetree/bindings/arm/idle-states.yaml
--
2.34.1
On Fri, 24 Dec 2021 15:48:34 +0100, David Heidelberg wrote:
> Merge Qualcomm specific idle-state binding with generic one.
>
> Signed-off-by: David Heidelberg <[email protected]>
>
> ---
> v3:
> - integrate into idle-state.yml
> - orig. patch name was:
> "[v2] dt-bindings: arm/msm/qcom,idle-state convert to YAML"
>
> Signed-off-by: David Heidelberg <[email protected]>
> ---
> .../devicetree/bindings/arm/idle-states.yaml | 107 ++++++++++++++++++
> .../bindings/arm/msm/qcom,idle-state.txt | 84 --------------
> 2 files changed, 107 insertions(+), 84 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
>
Running 'make dtbs_check' with the schema in this patch gives the
following warnings. Consider if they are expected or the schema is
incorrect. These may not be new warnings.
Note that it is not yet a requirement to have 0 warnings for dtbs_check.
This will change in the future.
Full log is available here: https://patchwork.ozlabs.org/patch/1573055
idle-states: 'clusteroff_b', 'clusteroff_l', 'cpuoff_b', 'cpuoff_l' do not match any of the regexes: '^(cpu|cluster)-', '^(ret|spc|pc)$', 'pinctrl-[0-9]+'
arch/arm64/boot/dts/mediatek/mt8192-evb.dt.yaml
idle-states: 'cluster_pd', 'core_pd' do not match any of the regexes: '^(cpu|cluster)-', '^(ret|spc|pc)$', 'pinctrl-[0-9]+'
arch/arm64/boot/dts/sprd/sp9860g-1h10.dt.yaml
idle-states: 'core-pd' does not match any of the regexes: '^(cpu|cluster)-', '^(ret|spc|pc)$', 'pinctrl-[0-9]+'
arch/arm64/boot/dts/sprd/sp9863a-1h10.dt.yaml
idle-states: cpu-sleep-0:compatible:0: 'arm,idle-state' was expected
arch/arm/boot/dts/qcom-msm8916-samsung-serranove.dt.yaml
idle-states: entry-method:0: 'psci' was expected
arch/arm64/boot/dts/mediatek/mt8192-evb.dt.yaml
idle-states: 'mpu_gate' does not match any of the regexes: '^(cpu|cluster)-', '^(ret|spc|pc)$', 'pinctrl-[0-9]+'
arch/arm/boot/dts/am335x-baltos-ir2110.dt.yaml
arch/arm/boot/dts/am335x-baltos-ir3220.dt.yaml
arch/arm/boot/dts/am335x-baltos-ir5221.dt.yaml
arch/arm/boot/dts/am335x-base0033.dt.yaml
arch/arm/boot/dts/am335x-boneblack.dt.yaml
arch/arm/boot/dts/am335x-boneblack-wireless.dt.yaml
arch/arm/boot/dts/am335x-boneblue.dt.yaml
arch/arm/boot/dts/am335x-bone.dt.yaml
arch/arm/boot/dts/am335x-bonegreen.dt.yaml
arch/arm/boot/dts/am335x-bonegreen-wireless.dt.yaml
arch/arm/boot/dts/am335x-chiliboard.dt.yaml
arch/arm/boot/dts/am335x-cm-t335.dt.yaml
arch/arm/boot/dts/am335x-evm.dt.yaml
arch/arm/boot/dts/am335x-evmsk.dt.yaml
arch/arm/boot/dts/am335x-guardian.dt.yaml
arch/arm/boot/dts/am335x-icev2.dt.yaml
arch/arm/boot/dts/am335x-lxm.dt.yaml
arch/arm/boot/dts/am335x-moxa-uc-2101.dt.yaml
arch/arm/boot/dts/am335x-moxa-uc-8100-me-t.dt.yaml
arch/arm/boot/dts/am335x-myirtech-myd.dt.yaml
arch/arm/boot/dts/am335x-nano.dt.yaml
arch/arm/boot/dts/am335x-netcan-plus-1xx.dt.yaml
arch/arm/boot/dts/am335x-netcom-plus-2xx.dt.yaml
arch/arm/boot/dts/am335x-netcom-plus-8xx.dt.yaml
arch/arm/boot/dts/am335x-osd3358-sm-red.dt.yaml
arch/arm/boot/dts/am335x-pdu001.dt.yaml
arch/arm/boot/dts/am335x-pepper.dt.yaml
arch/arm/boot/dts/am335x-phycore-rdk.dt.yaml
arch/arm/boot/dts/am335x-pocketbeagle.dt.yaml
arch/arm/boot/dts/am335x-regor-rdk.dt.yaml
arch/arm/boot/dts/am335x-sancloud-bbe.dt.yaml
arch/arm/boot/dts/am335x-sancloud-bbe-lite.dt.yaml
arch/arm/boot/dts/am335x-sbc-t335.dt.yaml
arch/arm/boot/dts/am335x-shc.dt.yaml
arch/arm/boot/dts/am335x-sl50.dt.yaml
arch/arm/boot/dts/am335x-wega-rdk.dt.yaml
arch/arm/boot/dts/am437x-cm-t43.dt.yaml
arch/arm/boot/dts/am437x-gp-evm.dt.yaml
arch/arm/boot/dts/am437x-idk-evm.dt.yaml
arch/arm/boot/dts/am437x-sbc-t43.dt.yaml
arch/arm/boot/dts/am437x-sk-evm.dt.yaml
arch/arm/boot/dts/am43x-epos-evm.dt.yaml
On Fri, Dec 24, 2021 at 03:48:34PM +0100, David Heidelberg wrote:
> Merge Qualcomm specific idle-state binding with generic one.
>
> Signed-off-by: David Heidelberg <[email protected]>
>
> ---
> v3:
> - integrate into idle-state.yml
> - orig. patch name was:
> "[v2] dt-bindings: arm/msm/qcom,idle-state convert to YAML"
>
> Signed-off-by: David Heidelberg <[email protected]>
> ---
> .../devicetree/bindings/arm/idle-states.yaml | 107 ++++++++++++++++++
> .../bindings/arm/msm/qcom,idle-state.txt | 84 --------------
> 2 files changed, 107 insertions(+), 84 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
>
> diff --git a/Documentation/devicetree/bindings/arm/idle-states.yaml b/Documentation/devicetree/bindings/arm/idle-states.yaml
> index 52bce5dbb11f..fde1557f2332 100644
> --- a/Documentation/devicetree/bindings/arm/idle-states.yaml
> +++ b/Documentation/devicetree/bindings/arm/idle-states.yaml
> @@ -241,6 +241,64 @@ description: |+
> [6] ARM Linux Kernel documentation - Booting AArch64 Linux
> Documentation/arm64/booting.rst
>
> + ===========================================
> + 5 - Qualcomm specific STATES
> + ===========================================
> +
> + cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle
What's cpuidle?
(Linux detail doesn't belong here)
> + states. Idle states have different enter/exit latency and residency values.
> + The idle states supported by the QCOM SoC are defined as -
> +
> + * Standby
> + * Retention
> + * Standalone Power Collapse (Standalone PC or SPC)
> + * Power Collapse (PC)
> +
> + Standby: Standby does a little more in addition to architectural clock gating.
> + When the WFI instruction is executed the ARM core would gate its internal
> + clocks. In addition to gating the clocks, QCOM cpus use this instruction as a
> + trigger to execute the SPM state machine. The SPM state machine waits for the
> + interrupt to trigger the core back in to active. This triggers the cache
> + hierarchy to enter standby states, when all cpus are idle. An interrupt brings
> + the SPM state machine out of its wait, the next step is to ensure that the
> + cache hierarchy is also out of standby, and then the cpu is allowed to resume
> + execution. This state is defined as a generic ARM WFI state by the ARM cpuidle
> + driver and is not defined in the DT. The SPM state machine should be
> + configured to execute this state by default and after executing every other
> + state below.
> +
> + Retention: Retention is a low power state where the core is clock gated and
> + the memory and the registers associated with the core are retained. The
> + voltage may be reduced to the minimum value needed to keep the processor
> + registers active. The SPM should be configured to execute the retention
> + sequence and would wait for interrupt, before restoring the cpu to execution
> + state. Retention may have a slightly higher latency than Standby.
> +
> + Standalone PC: A cpu can power down and warmboot if there is a sufficient time
> + between the time it enters idle and the next known wake up. SPC mode is used
> + to indicate a core entering a power down state without consulting any other
> + cpu or the system resources. This helps save power only on that core. The SPM
> + sequence for this idle state is programmed to power down the supply to the
> + core, wait for the interrupt, restore power to the core, and ensure the
> + system state including cache hierarchy is ready before allowing core to
> + resume. Applying power and resetting the core causes the core to warmboot
> + back into Elevation Level (EL) which trampolines the control back to the
> + kernel. Entering a power down state for the cpu, needs to be done by trapping
> + into a EL. Failing to do so, would result in a crash enforced by the warm boot
> + code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to
> + be flushed in s/w, before powering down the core.
> +
> + Power Collapse: This state is similar to the SPC mode, but distinguishes
> + itself in that the cpu acknowledges and permits the SoC to enter deeper sleep
> + modes. In a hierarchical power domain SoC, this means L2 and other caches can
> + be flushed, system bus, clocks - lowered, and SoC main XO clock gated and
> + voltages reduced, provided all cpus enter this state. Since the span of low
> + power modes possible at this state is vast, the exit latency and the residency
> + of this low power mode would be considered high even though at a cpu level,
> + this essentially is cpu power down. The SPM in this state also may handshake
> + with the Resource power manager (RPM) processor in the SoC to indicate a
> + complete application processor subsystem shut down.
I'm on the fence whether any of this belongs here... But I don't have a
better suggestion.
> +
> properties:
> $nodename:
> const: idle-states
> @@ -323,6 +381,44 @@ patternProperties:
> - exit-latency-us
> - min-residency-us
>
> + "^(ret|spc|pc)$":
Either these need to be added to the existing pattern for node names or
the node names in the dts files be changed to match the existing
binding. I think it is safe to do the latter as the driver doesn't care
about node names.
And then you just need to update the 'compatible' schema.
> + type: object
> + description:
> + Each state node represents a domain idle state description.
> +
> + properties:
> + compatible:
> + items:
> + - enum:
> + - qcom,idle-state-ret
> + - qcom,idle-state-spc
> + - qcom,idle-state-pc
> + - const: arm,idle-state
> +
> + entry-latency-us:
> + description:
> + The worst case latency in microseconds required to enter the idle
> + state. Note that, the exit-latency-us duration may be guaranteed only
> + after the entry-latency-us has passed.
> +
> + exit-latency-us:
> + description:
> + The worst case latency in microseconds required to exit the idle
> + state.
> +
> + min-residency-us:
> + description:
> + The minimum residency duration in microseconds after which the idle
> + state will yield power benefits, after overcoming the overhead while
> + entering the idle state.
> +
> + required:
> + - compatible
> + - entry-latency-us
> + - exit-latency-us
> + - min-residency-us
> +
> +
> additionalProperties: false
>
> examples:
> @@ -658,4 +754,15 @@ examples:
> };
> };
>
> + - |
> + // Example 3 - QCOM SPC
> + idle-states {
> + cpu_spc: spc {
> + compatible = "qcom,idle-state-spc", "arm,idle-state";
> + entry-latency-us = <150>;
> + exit-latency-us = <200>;
> + min-residency-us = <2000>;
> + };
> + };
> +
> ...
Thank you for the feedback, I tried to incorporate it and sent V4.
David
On 04/01/2022 21:49, Rob Herring wrote:
> On Fri, Dec 24, 2021 at 03:48:34PM +0100, David Heidelberg wrote:
>> Merge Qualcomm specific idle-state binding with generic one.
>>
>> Signed-off-by: David Heidelberg <[email protected]>
>>
>> ---
>> v3:
>> - integrate into idle-state.yml
>> - orig. patch name was:
>> "[v2] dt-bindings: arm/msm/qcom,idle-state convert to YAML"
>>
>> Signed-off-by: David Heidelberg <[email protected]>
>> ---
>> .../devicetree/bindings/arm/idle-states.yaml | 107 ++++++++++++++++++
>> .../bindings/arm/msm/qcom,idle-state.txt | 84 --------------
>> 2 files changed, 107 insertions(+), 84 deletions(-)
>> delete mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
>>
>> diff --git a/Documentation/devicetree/bindings/arm/idle-states.yaml b/Documentation/devicetree/bindings/arm/idle-states.yaml
>> index 52bce5dbb11f..fde1557f2332 100644
>> --- a/Documentation/devicetree/bindings/arm/idle-states.yaml
>> +++ b/Documentation/devicetree/bindings/arm/idle-states.yaml
>> @@ -241,6 +241,64 @@ description: |+
>> [6] ARM Linux Kernel documentation - Booting AArch64 Linux
>> Documentation/arm64/booting.rst
>>
>> + ===========================================
>> + 5 - Qualcomm specific STATES
>> + ===========================================
>> +
>> + cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle
> What's cpuidle?
>
> (Linux detail doesn't belong here)
>
>> + states. Idle states have different enter/exit latency and residency values.
>> + The idle states supported by the QCOM SoC are defined as -
>> +
>> + * Standby
>> + * Retention
>> + * Standalone Power Collapse (Standalone PC or SPC)
>> + * Power Collapse (PC)
>> +
>> + Standby: Standby does a little more in addition to architectural clock gating.
>> + When the WFI instruction is executed the ARM core would gate its internal
>> + clocks. In addition to gating the clocks, QCOM cpus use this instruction as a
>> + trigger to execute the SPM state machine. The SPM state machine waits for the
>> + interrupt to trigger the core back in to active. This triggers the cache
>> + hierarchy to enter standby states, when all cpus are idle. An interrupt brings
>> + the SPM state machine out of its wait, the next step is to ensure that the
>> + cache hierarchy is also out of standby, and then the cpu is allowed to resume
>> + execution. This state is defined as a generic ARM WFI state by the ARM cpuidle
>> + driver and is not defined in the DT. The SPM state machine should be
>> + configured to execute this state by default and after executing every other
>> + state below.
>> +
>> + Retention: Retention is a low power state where the core is clock gated and
>> + the memory and the registers associated with the core are retained. The
>> + voltage may be reduced to the minimum value needed to keep the processor
>> + registers active. The SPM should be configured to execute the retention
>> + sequence and would wait for interrupt, before restoring the cpu to execution
>> + state. Retention may have a slightly higher latency than Standby.
>> +
>> + Standalone PC: A cpu can power down and warmboot if there is a sufficient time
>> + between the time it enters idle and the next known wake up. SPC mode is used
>> + to indicate a core entering a power down state without consulting any other
>> + cpu or the system resources. This helps save power only on that core. The SPM
>> + sequence for this idle state is programmed to power down the supply to the
>> + core, wait for the interrupt, restore power to the core, and ensure the
>> + system state including cache hierarchy is ready before allowing core to
>> + resume. Applying power and resetting the core causes the core to warmboot
>> + back into Elevation Level (EL) which trampolines the control back to the
>> + kernel. Entering a power down state for the cpu, needs to be done by trapping
>> + into a EL. Failing to do so, would result in a crash enforced by the warm boot
>> + code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to
>> + be flushed in s/w, before powering down the core.
>> +
>> + Power Collapse: This state is similar to the SPC mode, but distinguishes
>> + itself in that the cpu acknowledges and permits the SoC to enter deeper sleep
>> + modes. In a hierarchical power domain SoC, this means L2 and other caches can
>> + be flushed, system bus, clocks - lowered, and SoC main XO clock gated and
>> + voltages reduced, provided all cpus enter this state. Since the span of low
>> + power modes possible at this state is vast, the exit latency and the residency
>> + of this low power mode would be considered high even though at a cpu level,
>> + this essentially is cpu power down. The SPM in this state also may handshake
>> + with the Resource power manager (RPM) processor in the SoC to indicate a
>> + complete application processor subsystem shut down.
> I'm on the fence whether any of this belongs here... But I don't have a
> better suggestion.
>
>> +
>> properties:
>> $nodename:
>> const: idle-states
>> @@ -323,6 +381,44 @@ patternProperties:
>> - exit-latency-us
>> - min-residency-us
>>
>> + "^(ret|spc|pc)$":
> Either these need to be added to the existing pattern for node names or
> the node names in the dts files be changed to match the existing
> binding. I think it is safe to do the latter as the driver doesn't care
> about node names.
>
> And then you just need to update the 'compatible' schema.
>
>> + type: object
>> + description:
>> + Each state node represents a domain idle state description.
>> +
>> + properties:
>> + compatible:
>> + items:
>> + - enum:
>> + - qcom,idle-state-ret
>> + - qcom,idle-state-spc
>> + - qcom,idle-state-pc
>> + - const: arm,idle-state
>> +
>> + entry-latency-us:
>> + description:
>> + The worst case latency in microseconds required to enter the idle
>> + state. Note that, the exit-latency-us duration may be guaranteed only
>> + after the entry-latency-us has passed.
>> +
>> + exit-latency-us:
>> + description:
>> + The worst case latency in microseconds required to exit the idle
>> + state.
>> +
>> + min-residency-us:
>> + description:
>> + The minimum residency duration in microseconds after which the idle
>> + state will yield power benefits, after overcoming the overhead while
>> + entering the idle state.
>> +
>> + required:
>> + - compatible
>> + - entry-latency-us
>> + - exit-latency-us
>> + - min-residency-us
>> +
>> +
>> additionalProperties: false
>>
>> examples:
>> @@ -658,4 +754,15 @@ examples:
>> };
>> };
>>
>> + - |
>> + // Example 3 - QCOM SPC
>> + idle-states {
>> + cpu_spc: spc {
>> + compatible = "qcom,idle-state-spc", "arm,idle-state";
>> + entry-latency-us = <150>;
>> + exit-latency-us = <200>;
>> + min-residency-us = <2000>;
>> + };
>> + };
>> +
>> ...
--
David Heidelberg