Re: [bug report] wifi: mt76: mt7925: iw set txpower fixed accepted but ignored

[Javier Tia]

On Sun May  4 22:04:48 2026 Bradley Pizzimenti wrote:
> `iw dev <iface> set txpower fixed N` returns success on mt7925 for
> any N tested, but the reported txpower never changes from a stuck
> value of 3.00 dBm.

Hi Bradley,

The 3 dBm display bug is a known issue we have seen when using mt7927
and a tested fix has been working well so far. The root cause is that
mt7925_mcu_set_rate_txpower() programs the per-band SKU tables into
firmware but never assigns phy->txpower_cur. mt76_get_txpower() then
computes:

  DIV_ROUND_UP(0 + 6, 2) = 3

regardless of the actual power level. The RF output is unaffected;
it is a display-only bug.

The fix reads the effective TX power back from the rate power limits
after programming the SKU tables and writes it to phy->txpower_cur,
following the same pattern used by mt7996:

  https://github.com/jetm/mediatek-mt7927-dkms/blob/master/mt7927-wifi-14-fix-reported-txpower-always-showing-3-db.patch

This is part of a series we are targeting for wireless-next; not
yet upstream.

> What seems potentially distinct here is that the user-issued
> `iw set txpower fixed N` itself is silently no-op'd, separate
> from the reported-value question.

Agreed those are two separate issues. Our patch addresses the
display-only side: after applying it, iw will report the value the
firmware is actually using based on the SKU tables, rather than
always 3 dBm. Whether `set txpower fixed N` propagates to firmware
to change actual output power is orthogonal and not addressed here.

If you can test the patch on your MT7925 and confirm the displayed
value reflects the correct power after association, a Tested-by
would be appreciated.

Best,
Javier