Re: [PATCH 2.6.39] mac80211: always clear PS filtering for non-AP interfaces

[Felix Fietkau <nbd@openwrt.org>]

On 2011-05-06 3:43 PM, Johannes Berg wrote:
> On Fri, 2011-05-06 at 15:35 +0200, Felix Fietkau wrote:
>
>>  >>   >>    +		info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
>
>>  Rely on what being set in AP mode only? The patch ensures that the flag
>>  for *clearing* PS filtering gets set for all non-AP modes. This flag
>>  already gets set whenever tx->sta is unset, so I think it also makes
>>  sense to extend that for other cases where the hardware is not supposed
>>  to enable any PS filtering on its own.
>
> I didn't remember/know about the case where sta is unset, but still,
> what if the driver checks for the flag and does something that's only
> valid in AP mode? I'm thinking firmware API here, not HW like ath9k.
>
>>  >  Your patch makes those drivers responsible for checking the mode, but
>>  >  that makes less sense than having drivers that need to do some magic in
>>  >  all modes, no?
>>  How does my patch make drivers responsible for checking the mode?
>
> Well, say I implement the clearing by sending something command to the
> device, like p54. If that's only valid in AP mode in the firmware, now
> this driver has to check that it's AP mode, where before it didn't have
> to. That's not counting the sta==NULL case I guess.
>
> OTOH, we only have two drivers using the flag anyway. Go figure it out
> between those two :)
mac80211 already sets the flag for all modes. If drivers were depending 
on it being set only for AP mode, then those drivers would break even 
without my patch.

- Felix