netdev - Re: [PATCH RFC] b43: stop hardcoding LED behavior

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Date:	Mon, 25 Apr 2016 17:53:26 +0200
From:	Michael Büsch <m@...s.ch>
To:	Lucas Stach <dev@...xeye.de>
Cc:	Kalle Valo <kvalo@...eaurora.org>, netdev@...r.kernel.org,
	linux-wireless@...r.kernel.org, b43-dev@...ts.infradead.org
Subject: Re: [PATCH RFC] b43: stop hardcoding LED behavior

On Mon, 25 Apr 2016 09:40:51 +0200
Lucas Stach <dev@...xeye.de> wrote:

> On my system the SPROM correctly defines the only wired LED (radio) but
> skips all others, leading to the hardcode to register LEDs with RX and TX
> triggers.

Hm ok. It probably is a good idea to change the condition from

if (sprom[led_index] == 0xFF)

to

if ((sprom[0] & sprom[1] & sprom[2] & sprom[3]) == 0xFF)

So the hardcoding only happens if there is no LED configured in the
SPROM. (I think my card does this (see below), but I can check that
later)


> These triggers cause many uneccesary CPU wakeups to drive LEDs
> that aren't even present in the system, reducing battery runtime.


Numbers please. Did you measure that is actually causes more _wakeups_?
How many?
The led work is placed in the mac80211 workqueue and LED updates only
happen on behalf of mac80211 activities (by default). It only causes
additional wakeups, if there's nothing else scheduled on the workqueue
anyways (which might well be the case. So we need numbers. :)


> Remove the hardcode to stop it from doing any harm. If this code is useful
> for others it should probably be reworked as a quirk table triggering only
> for individual systems that need it.


There are cards that need it. I don't know how many that are, but I own
an older 4306 PC-Card card that needs this.

So this effectively is a regression for this card.

So I don't think this is acceptable.
You should at least make this configurable via module parameter or such.
Or maybe the change from above already is enough. It should work for
your case.


> Signed-off-by: Lucas Stach <dev@...xeye.de>
> ---
>  drivers/net/wireless/broadcom/b43/leds.c | 26 ++------------------------
>  1 file changed, 2 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/b43/leds.c b/drivers/net/wireless/broadcom/b43/leds.c
> index d79ab2a..77d2dad 100644
> --- a/drivers/net/wireless/broadcom/b43/leds.c
> +++ b/drivers/net/wireless/broadcom/b43/leds.c
> @@ -224,31 +224,9 @@ static void b43_led_get_sprominfo(struct b43_wldev *dev,
>  
>  	if (sprom[led_index] == 0xFF) {
>  		/* There is no LED information in the SPROM
> -		 * for this LED. Hardcode it here. */
> +		 * for this LED. Keep it disabled. */
>  		*activelow = false;
> -		switch (led_index) {
> -		case 0:
> -			*behaviour = B43_LED_ACTIVITY;
> -			*activelow = true;
> -			if (dev->dev->board_vendor == PCI_VENDOR_ID_COMPAQ)
> -				*behaviour = B43_LED_RADIO_ALL;
> -			break;
> -		case 1:
> -			*behaviour = B43_LED_RADIO_B;
> -			if (dev->dev->board_vendor == PCI_VENDOR_ID_ASUSTEK)
> -				*behaviour = B43_LED_ASSOC;
> -			break;
> -		case 2:
> -			*behaviour = B43_LED_RADIO_A;
> -			break;
> -		case 3:
> -			*behaviour = B43_LED_OFF;
> -			break;
> -		default:
> -			*behaviour = B43_LED_OFF;
> -			B43_WARN_ON(1);
> -			return;
> -		}
> +		*behaviour = B43_LED_OFF;
>  	} else {
>  		*behaviour = sprom[led_index] & B43_LED_BEHAVIOUR;
>  		*activelow = !!(sprom[led_index] & B43_LED_ACTIVELOW);




-- 
Michael

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