Re: [PATCH] cfg80211: restrict AP beacon intervals

[Ben Greear <greearb@candelatech.com>]

On 05/09/2011 09:49 AM, Johannes Berg wrote:
> On Mon, 2011-05-09 at 09:46 -0700, Ben Greear wrote:
>> On 05/09/2011 09:41 AM, Johannes Berg wrote:
>>> From: Johannes Berg<johannes.berg@intel.com>
>>>
>>> Multiple virtual AP interfaces can currently try
>>> to use different beacon intervals, but that just
>>> leads to problems since it won't actually be done
>>> that way by drivers. Return an error in this case
>>> to make sure it won't be done wrong.
>>
>> I think there is no problem with having different beacon
>> intervals, as long as they are all a multiple of
>> the smallest interval and the driver does things properly.
>>
>> I'm not sure ath9k or ath5k currently supports this properly,
>> but there was a patch floating around for a while that did
>> this for ath9k I think...
>
> Yes, in theory that's possible, but apparently no driver actually did
> this correctly. Also, it didn't seem like anyone really cares, and we
> need to enforce some restrictions because otherwise drivers will end up
> doing it wrong, and you'll end up having a beacon interval of 200 while
> advertising 150 for example, which will totally throw off powersaving
> clients.
>
> If you really care greatly about having different beacon intervals (and
> I don't see why you would?) then maybe you can think how we can enforce
> and advertise that to userspace. For now, I'm more comfortable just
> restricting it.

I guess we could add a flag to the driver when it supports it properly
and modify your logic to check for even multiples instead of just ==
if that flag is set?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com