please consider adding FIRMWARE_FLOW_CTRL to radio.conf

[hlyi]

@jnilo1 Do you think adding FIRMWARE_FLOW_CTRL automatically to radio.conf based upon board type makes sense to you? Thanks

[jnilo1]

Yes — agreed, and it fits the existing design

Good suggestion. flash_efr32.sh already treats radio.conf as the record of the chip-side truth written at flash time: it persists FIRMWARE=, FIRMWARE_VERSION=, FIRMWARE_BAUD= and MODE= after every successful flash, precisely so the init scripts and the humans never have to guess what is on the radio. FIRMWARE_FLOW_CTRL is the one chip-side fact that is currently left for the user to add by hand, even though the build system already knows it: boards/<board>/board.env carries BOARD_UART_FLOW (hw for the Lidl reference, sw for the G4).

What will change

For app-slot flashes (NCP / RCP / OT-RCP / Router — not bootloader-only), flash_efr32.sh will read BOARD_UART_FLOW from the selected board's board.env and write FIRMWARE_FLOW_CTRL=<hw|sw|none> into /userdata/etc/radio.conf, following the same strip-then-append pattern as the other keys it owns. Consumers are already in place:

• S50uart_bridge maps it onto the in-kernel bridge's tri-state flow_control;
• S70otbr maps none|sw to uart-flow-control=false on the spinel URL (hw or absent → true).

So on a G4, flashing any radio firmware will automatically leave the host side configured for no RTS/CTS, with nothing to edit manually.

Timing

Queued for v4.0.0. Note that we will not publish any new release candidate until issue #99 is definitively closed (rc4 is under field validation), so this will ship with v4.0.0 directly.

[jnilo1]

Implemented

This is now implemented, exactly along the lines described above. Every application flash (NCP / RCP / OT-RCP / Router) writes FIRMWARE_FLOW_CTRL=<hw|sw|none> into /userdata/etc/radio.conf, taking the value from the selected board's boards/<board>/board.env (BOARD_UART_FLOW — hw for lidl, sw for sengled-e39-g8c), with the same strip-then-append pattern as the other keys the script owns. The value is validated at board-selection time, so a malformed third-party board.env fails fast before anything touches the gateway. Bootloader-only flashes are unchanged — they keep touching only BOOTLOADER_VERSION=.

For a Lidl user this is behaviourally a no-op (hw is what the devicetree default and S70otbr's absent-key fallback already selected). On a G4, flashing any radio firmware now leaves the host side configured for XON/XOFF automatically — the manual FIRMWARE_FLOW_CTRL=sw step for OT-RCP is gone.

One deliberate consequence to be aware of: a hand-edited FIRMWARE_FLOW_CTRL is reset to the board default at each application flash. That only matters if you flash an exotic image via --firmware-file whose flow mode differs from the board's — re-apply the key afterwards in that case.

Timing

As stated above, this ships with v4.0.0 — no new release candidate before issue #99 is definitively closed.

[hlyi]

Thanks @jnilo1! you implemented in this v4.0.0-rc5. close the discussion.