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From: Arik Nemtsov <arik@wizery.com>
Date: Thu, 4 Nov 2010 07:34:01 +0200
Message-ID: <AANLkTimXwopqOUcBWxwAmEH1tJbtLQisW7dmm+XDWHPe@mail.gmail.com>
Subject: Re: [PATCH 3/4] mac80211: don't fragment packets when
 HW-fragmentation is on
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org,
	Luciano Coelho <luciano.coelho@nokia.com>
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Sender: linux-wireless-owner@vger.kernel.org

On Thu, Nov 4, 2010 at 04:15, Johannes Berg <johannes@sipsolutions.net> wrote:
>
> On Wed, 2010-11-03 at 23:50 +0200, Arik Nemtsov wrote:
> > If the driver supports hardware TX fragmentation, don't fragment
> > packets in the stack.
>
> I'm not sure why you have three patches? Seems like it could all be a
> single mac80211 patch.

Sure. I'll send a v2 with the mac80211 patches bundled into a single one.

>
> > @@ -1181,8 +1183,10 @@ ieee80211_tx_prepare(struct ieee80211_sub_if_data *sdata,
> > ? ? ? /*
> > ? ? ? ?* Set this flag (used below to indicate "automatic fragmentation"),
> > ? ? ? ?* it will be cleared/left by radiotap as desired.
> > + ? ? ?* Only valid when fragmentation is done by the stack.
> > ? ? ? ?*/
> > - ? ? tx->flags |= IEEE80211_TX_FRAGMENTED;
> > + ? ? if (!(local->hw.flags & IEEE80211_HW_TX_FRAGMENTATION))
> > + ? ? ? ? ? ? tx->flags |= IEEE80211_TX_FRAGMENTED;
>
> Do we really need the hw flag? Couldn't we go off the callback, like we
> used to? I'm not really sure which one would perform better though, I
> guess the flag might ...

I think the flag may be less confusing for new driver writers.
Someone can implement the callback as a no-op and have a bug in his
code as a result.

Regards,
Arik