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Subject: Re: [PATCH 1/4] mac80211: Convert PS configuration from a binary
 flag to a set of modes
From: Johannes Berg <johannes@sipsolutions.net>
To: Arend van Spriel <arend@broadcom.com>
Cc: Seth Forshee <seth.forshee@canonical.com>,
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Date: Wed, 13 Feb 2013 20:09:42 +0100
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On Wed, 2013-02-13 at 19:54 +0100, Arend van Spriel wrote:
> On 02/13/2013 06:04 PM, Seth Forshee wrote:
> >> Is all this really worth it? It seems a quick fix for brcmsmac might be
> >> > to always set the powersave bit when IEEE80211_CONF_OFFCHANNEL is
> >> > enabled in the config, and then go implement a real solution like I
> >> > described earlier with powersave being separated out of the core
> >> > mac80211 routines, and actually made possible for multiple interfaces?
> > Using IEEE80211_CONF_OFFCHANNEL won't work. When the nullfunc to enable
> > PS is sent the flag won't be set, as we're still on the operating
> > channel. When we're actually off-channel the value of PM doesn't matter
> > for the types of frames which are being sent. The only quick fix I've
> > found is to watch out for frames with PM set and set the powersave bit
> > while they're being transmitted.
> 
> I actually don't see that one fly. The frames are posted on a DMA fifo
> towards the hardware so in the driver we have no clue when that frame is
> being processes/transmitted hence no way of knowing when to write the
> register(s).

I think the various flushing would prevent issues there, no?

johannes