PROTOCOLS
Device
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
GetCurrentOperatingPoint
Gets the current operating point of the device.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
out_opp |
uint32
|
GetCurrentOperatingPointLimits
Returns the current minimum and maximum operating point limits.
Returns ZX_OK on success.
Returns ZX_ERR_NOT_SUPPORTED if the device does not support limits.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
payload |
Device_GetCurrentOperatingPointLimits_Result
|
GetDomainId
Returns the id of this performance domain within its package. This number should be stable across boots, but clients should prefer to use GetRelativePerformance to differentiate cores if possible.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
domain_id |
uint32
|
GetLogicalCoreId
Returns a global system-wide core ID for the nth core in this
performance domain. index must be a value in the range [0, n) where
n is the value returned by GetNumLogicalCores().
Request
| Name | Type |
|---|---|
index |
uint64
|
Response
| Name | Type |
|---|---|
id |
uint64
|
GetNumLogicalCores
Returns the number of logical cores contained within this performance domain.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
count |
uint64
|
GetOperatingPointCount
Returns the number of operating points within this performance domain.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
payload |
Device_GetOperatingPointCount_Result
|
GetOperatingPointInfo
Returns information about a given operating point for this performance domain.
Request
| Name | Type |
|---|---|
opp |
uint32
|
Response
| Name | Type |
|---|---|
payload |
Device_GetOperatingPointInfo_Result
|
GetRelativePerformance
The relative performance of this domain as configured by the platform, if known. The highest performance domain should return 255, while others should return N/255 fractional values relative to that domain. Returns ZX_ERR_NOT_SUPPORTED if the performance level is unknown.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
payload |
Device_GetRelativePerformance_Result
|
SetCurrentOperatingPoint
Set the operating point of this device to the requested operating point.
Operating points are in numeric P-state order, such that the maximum operating performance point is 0 and the minimum is n-1, where n is the number of operating points returned by GetOperatingPointCount().
The requested operating point may be clamped to the range [min, max] when operating point limits are supported. See SetOperatingPointLimits for details.
Returns ZX_OK, if the device is in a working state and the operating point is changed to requested_opp successfully. out_opp will be same as requested_opp.
Returns ZX_ERR_OUT_OF_RANGE if the minimum_opp is outside of the range [n-1, 0], where n is the number of operating points returned by GetOperatingPointCount().
Returns error status, if switching to the requested_opp was unsuccessful. out_opp is the operating performance point (OPP) that the device is currently in.
Request
| Name | Type |
|---|---|
requested_opp |
uint32
|
Response
| Name | Type |
|---|---|
payload |
Device_SetCurrentOperatingPoint_Result
|
SetMaximumOperatingPointLimit
Sets the maximum operating point to use, particularly when the kernel automatically controls the operating points of this device.
See SetOperatingPointLimits for details on the semantics of operating point limits.
Returns ZX_OK on success.
Returns ZX_ERR_OUT_OF_RANGE if the maximum_opp is outside of the range [n-1, 0], where n is the number of operating points returned by GetOperatingPointCount().
Returns ZX_ERR_NOT_SUPPORTED if the device does not support limits.
Request
| Name | Type |
|---|---|
maximum_opp |
uint32
|
Response
| Name | Type |
|---|---|
payload |
Device_SetMaximumOperatingPointLimit_Result
|
SetMinimumOperatingPointLimit
Sets the minimum operating point to use, particularly when the kernel automatically controls the operating points of this device.
See SetOperatingPointLimits for details on the semantics of operating point limits.
Returns ZX_OK on success.
Returns ZX_ERR_OUT_OF_RANGE if the minimum_opp is outside of the range [n-1, 0], where n is the number of operating points returned by GetOperatingPointCount().
Returns ZX_ERR_NOT_SUPPORTED if the device does not support limits.
Request
| Name | Type |
|---|---|
minimum_opp |
uint32
|
Response
| Name | Type |
|---|---|
payload |
Device_SetMinimumOperatingPointLimit_Result
|
SetOperatingPointLimits
Sets the operational boundaries (minimum and maximum operating points) for the device, when supported.
Limits define the allowable performance range for the performance domain. They are primarily used for:
- Thermal Mitigation: Progressively lowering the maximum operating point (moving from 0 toward n-1) to reduce power dissipation.
- Performance Boosting: Raising the minimum operating point (moving from n-1 toward 0) when automatic performance matching is insufficient for the current workload.
Limits are useful on platforms where ether hardware or the kernel automatically manages performance. By setting boundaries, userspace can enforce power and performance policies while allowing the underlying system to react to high-fidelity signals in real-time.
When limits are applied, the active operating point is clamped to the range:
[max(minimum_opp, maximim_opp), maximum_opp].
Note that maximim_opp and minimum_opp reside in the P-state range [n-1, 0].
This logic ensures that the minimum_opp can be adjusted independently while
always respecting the ceiling imposed by the maximim_opp.
Set the operating point limits to (n-1, 0) to effectively remove the limits.
Returns ZX_OK on success.
Returns ZX_ERR_OUT_OF_RANGE if the minimum_opp or maximum_opp is outside of the range [n-1, 0], where n is the number of operating points returned by GetOperatingPointCount().
Returns ZX_ERR_NOT_SUPPORTED if the device does not support limits.
Request
| Name | Type |
|---|---|
minimum_opp |
uint32
|
maximum_opp |
uint32
|
Response
| Name | Type |
|---|---|
payload |
Device_SetOperatingPointLimits_Result
|
STRUCTS
CpuOperatingPointInfo
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
A collection of some basic information for a given operating point.
| Field | Type | Description | Default |
|---|---|---|---|
frequency_hz |
int64
|
No default | |
voltage_uv |
int64
|
No default |
Device_GetCurrentOperatingPointLimits_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Field | Type | Description | Default |
|---|---|---|---|
minimum_opp |
uint32
|
No default | |
maximum_opp |
uint32
|
No default |
Device_GetOperatingPointCount_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Field | Type | Description | Default |
|---|---|---|---|
count |
uint32
|
No default |
Device_GetOperatingPointInfo_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Field | Type | Description | Default |
|---|---|---|---|
info |
CpuOperatingPointInfo
|
No default |
Device_GetRelativePerformance_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Field | Type | Description | Default |
|---|---|---|---|
relative_performance |
uint8
|
No default |
Device_SetCurrentOperatingPoint_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Field | Type | Description | Default |
|---|---|---|---|
out_opp |
uint32
|
No default |
Device_SetMaximumOperatingPointLimit_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
<EMPTY>
Device_SetMinimumOperatingPointLimit_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
<EMPTY>
Device_SetOperatingPointLimits_Response
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
<EMPTY>
UNIONS
Device_GetCurrentOperatingPointLimits_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_GetCurrentOperatingPointLimits_Response
|
|
2 |
err |
zx/Status
|
Device_GetOperatingPointCount_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_GetOperatingPointCount_Response
|
|
2 |
err |
zx/Status
|
Device_GetOperatingPointInfo_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_GetOperatingPointInfo_Response
|
|
2 |
err |
zx/Status
|
Device_GetRelativePerformance_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_GetRelativePerformance_Response
|
|
2 |
err |
zx/Status
|
Device_SetCurrentOperatingPoint_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_SetCurrentOperatingPoint_Response
|
|
2 |
err |
zx/Status
|
Device_SetMaximumOperatingPointLimit_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_SetMaximumOperatingPointLimit_Response
|
|
2 |
err |
zx/Status
|
Device_SetMinimumOperatingPointLimit_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_SetMinimumOperatingPointLimit_Response
|
|
2 |
err |
zx/Status
|
Device_SetOperatingPointLimits_Result strict
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
Device_SetOperatingPointLimits_Response
|
|
2 |
err |
zx/Status
|
CONSTANTS
| Name | Value | Type | Description |
|---|---|---|---|
| DEVICE_OPERATING_POINT_P0 |
0
|
uint32 |
|
| FREQUENCY_UNKNOWN |
-1
|
int64 |
CpuOperatingPointInfo::frequency_hz and CpuOperatingPointInfo::voltage_uv are set to this if the frequency and voltage for the given operating point are unknown respectively. |
| VOLTAGE_UNKNOWN |
-1
|
int64 |
SERVICES
Service
Defined in fuchsia.hardware.cpu.ctrl/ctrl.fidl
| Name | Type | Transport |
|---|---|---|
| device |
fuchsia.hardware.cpu.ctrl/Device
|
Channel |