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Device Frequency and Power are only indication to OSPM for the performance levels and OSPM should not rely on the values.
_DPC
OSPM can use this method to choose a performance level for the device.
| Code Block |
|---|
Method(_DPC, 1, Serialized)
{
...
} |
_DPU
OSPM can use this method to get the device indica’s current utilization in percentage.
...
_DPA will return the first available Px index that OSPM can use for dynamic performance level setting.
_DPD
OSPM can use this method to get the delivered performance level.
| Code Block |
|---|
Method(_DPD)
{
Return <Px index>
} |
This method is optional if ClockInput resources are provided for the device in _CRS method.
Example with I.MX8MP DDR Controller
Device utilization is derived from PMU counters.
TF-A implements functions that can be invoked from AML via FFH and /SMCC to collect the device utilization and configure the DDR frequency.
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