Return-path: Received: from fk-out-0910.google.com ([209.85.128.191]:10027 "EHLO fk-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751980AbYAVTyg (ORCPT ); Tue, 22 Jan 2008 14:54:36 -0500 Received: by fk-out-0910.google.com with SMTP id z23so1850683fkz.5 for ; Tue, 22 Jan 2008 11:54:32 -0800 (PST) To: "Luis R. Rodriguez" Subject: Re: [PATCH] mac80211: enable IBSS merging Date: Tue, 22 Jan 2008 20:54:22 +0100 Cc: "bruno randolf" , "Johannes Berg" , "Michael Wu" , ath5k-devel@lists.ath5k.org, jirislaby@gmail.com, mickflemm@gmail.com, linux-wireless@vger.kernel.org, linville@tuxdriver.com, "Ulrich Kunitz" , "Daniel Drake" References: <20080118125252.6455.41047.stgit@one> <200801211705.24221.IvDoorn@gmail.com> <43e72e890801221147uedf8002oc21840bdd80a157c@mail.gmail.com> In-Reply-To: <43e72e890801221147uedf8002oc21840bdd80a157c@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Message-Id: <200801222054.23433.IvDoorn@gmail.com> (sfid-20080122_195440_288971_1CCC8A4D) From: Ivo van Doorn Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi, > > > > Then there is a problem for rt2x00. Since the mactime isn't known. > > > > rt2400pci is the _only_ device which has a RX_END_TIME field in the > > > > RX descriptor. > > > > > > one workaround could be to simply use the current TSF at the time in the > > > tasklet or interrupt handler (to be more close to the actual rx time). this > > > should be sufficient to catch most cases where an IBSS merge is necessary - > > > usually the beacon's TSF will be much higher than the local TSF. > > > > Should the driver to this, or should mac80211 handle that? > > The driver should if it has access to some the mactime of the received > packet otherwise yes -- I think mac80211 can handle this using the > supplied get_tsf(). > > > Personally I think it is something for the mac80211 layer since the driver will > > give what it can, and can be sure that it is what mac80211 expects instead of > > drivers interpreting what mac80211 might want as replacement. > > If mac80211 needs the TSF value when no mac time is given, it could just > > use the get_tsf() callback function to the driver to get the substitute. When the > > get_tsf() callback is not provided, then mac80211 can complain about missing > > information. > > Agreed, how about something like this modified to Bruno's patch: > > + if (rx_status->flag & RX_FLAG_TSFT) > + mactime = rx_status->mactime; > + else { > + if (!local->ops->get_tsf) { > + WARN_ON(1); > + mactime = -1LLU; > + if (net_ratelimit()) > + printk(KERN_WARNING "%s: cannot determine if " > + "IBSS merge is required", dev->name); > + } > + else { > + if (net_ratelimit()) > + printk("Could not get detailed timestamp > of beacon " > + during reception, using the > driver's TSF timer for mactime\n") > + mactime = local->ops->get_tsf(local_to_hw(local)); > + } > + } > > We could just not support IBSS for driver's without a get_tsf(). Thoughts? I am not sure if we should print error warning messages when the mactime is not provided. But other then that I agree with the above change, as it would allow rt2x00 to use the IBSS syncing. :) Ivo