Sven Kirmess
a61151a5d0
The radio URL can configure the CCA threshold, the FEM LNA gain, the region and a per-channel power cap, but not the power the radio actually transmits at. `ot-ctl txpower` sets it at runtime only, so a deployment cannot be brought up from its configuration alone -- something has to issue a CLI command after every start. `max-power-table` does not cover this. It is a cap: the effective power is `min(txPower, channelMax)`, so it can lower the power but never raise it above whatever the RCP happens to be at. Nothing on the host sets that power during initialisation, and OPENTHREAD_CONFIG_DEFAULT_TRANSMIT_POWER is consumed by the platform layer rather than here, so an RCP-based deployment runs at whatever constant its RCP firmware was built with. This adds `tx-power[=dbm]`, applied during radio initialisation next to `cca-threshold` and `fem-lnagain`. The two combine rather than override: the radio transmits at `min(tx-power, max-power-table)`, which the help text spells out -- conditionally, since `max-power-table` is itself behind OPENTHREAD_POSIX_CONFIG_MAX_POWER_TABLE_ENABLE and a build without it would otherwise point at a parameter its own help does not list. `tests/scripts/expect/posix-tx-power.exp` covers it, following posix-ccathreshold.exp: two valid values, the two int8 boundaries that must be rejected, and a run without the parameter that must report 0 dBm -- without that last case the test could not tell a value that came from the radio URL from one the radio happened to be at. Because it goes through `RadioSpinel::SetTransmitPower()`, it also lands in the restoration bookkeeping and survives an RCP reset. Measured against a simulated RCP: tx-power=11 ot-ctl txpower -> 11 dBm no parameter ot-ctl txpower -> 0 dBm and against an SLZB-06M (EFR32, SL-OPENTHREAD/2.4.2.0), with the radio deliberately set to 5 dBm beforehand so neither the default nor a retained value could explain the result: tx-power=11 ot-ctl txpower -> 10 dBm 10 rather than 11 because the EFR32 selects the nearest step at or below the requested power; 5 reads back as 4 for the same reason. Closes #13573
What is OpenThread?
OpenThread released by Google is... 
...an open-source implementation of the Thread networking protocol. Google Nest has released OpenThread to make the technology used in Nest products more broadly available to developers to accelerate the development of products for the connected home.
...OS and platform agnostic, with a narrow platform abstraction layer and a small memory footprint, making it highly portable. It supports both system-on-chip (SoC) and network co-processor (NCP) designs.
...a Thread Certified Component, implementing all features defined in the Thread 1.4.0 specification, including all Thread networking layers (IPv6, 6LoWPAN, IEEE 802.15.4 with MAC security, Mesh Link Establishment, Mesh Routing) and device roles, as well as Border Router support.
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