Implement setting TX_GAIN_LORA for portduino

[Stary2001]

I've implemented support for TX_GAIN_LORA in the portduino yaml config. Also refactors the code a little bit to support choosing linear/nonlinear gain at runtime for this.
Tested with this config:

Lora:
 Module: sx1262
 DIO2_AS_RF_SWITCH: true
 DIO3_TCXO_VOLTAGE: true
 CS: 8
 IRQ: 27
 Busy: 22
 Reset: 23
 TX_GAIN_LORA: 20
 SX1262_MAX_POWER: 12

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • native
  • T1000E

[Copilot]

Pull Request Overview

This pull request implements support for configuring TX_GAIN_LORA values through the portduino YAML configuration file, adding the ability to specify either a single gain value or an array of values for nonlinear power amplifiers. The implementation refactors the existing compile-time TX_GAIN_LORA handling to support runtime configuration on portduino platforms.

Key Changes:

• Added num_pa_points and tx_gain_lora[] array to portduino configuration structure
• Unified linear and nonlinear gain handling in RadioInterface to work with both compile-time (non-portduino) and runtime (portduino) configurations
• Added YAML parsing and serialization for the new TX_GAIN_LORA configuration field

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/platform/portduino/PortduinoGlue.h	Added struct members for storing TX_GAIN_LORA values and YAML serialization logic
src/platform/portduino/PortduinoGlue.cpp	Implemented YAML parsing for TX_GAIN_LORA configuration (single value or array)
src/mesh/RadioInterface.cpp	Refactored power limiting logic to support both compile-time and runtime TX_GAIN_LORA values
src/configuration.h	Added default NUM_PA_POINTS definition

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.