Krzysztof Kozlowski [off-list ref] wrote:

After commit 72cdab808714 ("ath9k: Do not select MAC80211_LEDS by
default") a configuration like:
 - MAC80211_LEDS=y
 - LEDS_CLASS=m
 - NEW_LEDS=y
 - ATH9K=y
leads to a build failure:

    /usr/bin/ld: drivers/net/wireless/ath/ath9k/gpio.o: in function `ath_deinit_leds':
    drivers/net/wireless/ath/ath9k/gpio.c:69: undefined reference to `led_classdev_unregister'
    /usr/bin/ld: drivers/net/wireless/ath/ath9k/gpio.o: in function `led_classdev_register':
    include/linux/leds.h:190: undefined reference to `led_classdev_register_ext'

To be able to use LED triggers, the LEDS_CLASS can only be a module
if ath9k driver is a module as well.

Reported-by: kernel test robot <redacted>
Fixes: 72cdab808714 ("ath9k: Do not select MAC80211_LEDS by default")
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

I took Arnd's patch instead:

https://patchwork.kernel.org/project/linux-wireless/patch/20210125113654.2408057-1-arnd@kernel.org/

But I think we really need the cleanup Arnd proposes during the discussion so
that we have consistent LED handling in wireless drivers. Patches very welcome.

Patch set to Superseded.

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20201227143034.1134829-1-krzk@kernel.org/

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