Arnd Bergmann [off-list ref] wrote:

From: Arnd Bergmann <arnd@arndb.de>

The dependencies for LED configuration are highly inconsistent and too
complicated at the moment. One of the results is a randconfig failure I
get very rarely when LEDS_CLASS is in a loadable module, but the wireless
core is built-in:

WARNING: unmet direct dependencies detected for MAC80211_LEDS
  Depends on [n]: NET [=y] && WIRELESS [=y] && MAC80211 [=y] && (LEDS_CLASS [=m]=y || LEDS_CLASS [=m]=MAC80211 [=y])
  Selected by [m]:
  - IWLEGACY [=m] && NETDEVICES [=y] && WLAN [=y] && WLAN_VENDOR_INTEL [=y]
  - IWLWIFI_LEDS [=y] && NETDEVICES [=y] && WLAN [=y] && WLAN_VENDOR_INTEL [=y] && IWLWIFI [=m] && (LEDS_CLASS [=m]=y || LEDS_CLASS [=m]=IWLWIFI [=m]) && (IWLMVM [=m] || IWLDVM [=m])

aarch64-linux-ld: drivers/net/wireless/ath/ath5k/led.o: in function `ath5k_register_led':
led.c:(.text+0x60): undefined reference to `led_classdev_register_ext'
aarch64-linux-ld: drivers/net/wireless/ath/ath5k/led.o: in function `ath5k_unregister_leds':
led.c:(.text+0x200): undefined reference to `led_classdev_unregister'

For iwlwifi, the dependency is wrong, since this config prevents the
MAC80211_LEDS code from being part of a built-in MAC80211 driver.

For iwlegacy, this is worse because the driver tries to force-enable
the other subsystems, which is both a layering violation and a bug
because it will still fail with MAC80211=y and IWLEGACY=m, leading
to LEDS_CLASS being a module as well.

The actual link failure in the ath5k driver is a result of MAC80211_LEDS
being enabled but not usable. With the Kconfig logic fixed in the
Intel drivers, the ath5k driver works as expected again.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Luca Coelho <redacted>

3 patches applied to wireless-drivers.git, thanks.

efdbfa0ad03e iwlwifi: fix LED dependencies
c68115fc5375 brcmsmac: rework LED dependencies
f7d55d2e439f mt76: mt7921: fix build regression

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20211204173848.873293-1-arnd@kernel.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches