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

[Sean Wang]

Hi,

The TX power reporting issue has already been investigated by Lucid
from the Linux WiFi USB community, and there is a proposed solution.
I think we can continue checking whether there are any remaining
issues on top of that work. Please refer to the patches here:
https://lists.infradead.org/pipermail/linux-mediatek/2026-April/105726.html
Thanks everyone for reporting and raising these concerns.

On Wed, May 6, 2026 at 3:09 PM Javier Tia <floss at jetm.me> wrote:
>
> 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
>