wifi: mt76: mt7921: assert sniffer on chanctx change

mt7921_change_chanctx() configures the channel for monitor vifs but
does not re-assert sniffer mode. mt7925_change_chanctx() does. Match
mt7925 by adding the missing mt7921_mcu_set_sniffer(true) call,
completing the architectural pattern from commit 914189af23 ("wifi:
mt76: mt7921: fix channel switch fail in monitor mode").

The user-visible regression this asymmetry produced on v6.17 and v6.18
was addressed by commit cdb2941a51 ("Revert "wifi: mt76: mt792x:
improve monitor interface handling"") in v6.19 and backported to the
6.17.y and 6.18.y stable trees. This patch is defense in depth in
case the NO_VIRTUAL_MONITOR change is reintroduced in a future series.

Tested-by: Nick Morrow <morrownr@gmail.com>
Tested-on: RasPi4B, RasPiOS 64 bit, Alfa AWUS036AXML mt7921u
Tested-on: RasPi4B, RasPiOS 64 bit, Netgear A9000 mt7925u
Signed-off-by: Devin Wittmayer <lucid_duck@justthetip.ca>
Link: https://patch.msgid.link/20260515183921.23484-1-lucid_duck@justthetip.ca
Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Devin Wittmayer 2026-05-15 11:39:21 -07:00 • committed by Felix Fietkau
commit a7d35545c2