linux-kernel - Re: Bisected 3.9 regression for iwl4965 connection problem to 1672c0e3

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Message-ID: <CANUX_P1n=A1rxDYyuQH=azYiTtuz=q-mh3zZeu_30bRUHjVzSA@mail.gmail.com>
Date:	Tue, 7 May 2013 11:46:07 +0300
From:	Emmanuel Grumbach <egrumbach@...il.com>
To:	Stanislaw Gruszka <sgruszka@...hat.com>
Cc:	Johannes Berg <johannes@...solutions.net>,
	Jake Edge <jake@....net>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: Bisected 3.9 regression for iwl4965 connection problem to 1672c0e3

>> > > But if so, I would also see
>> > > the breakage on my setup, but I don't - it works quite well here.
>> >
>> > Are you testing on a passive channel? Try with a large beacon interval.
>>
>> I think most likely what happens is that it's on a passive channel, and
>> the firmware drops the TX packet with a bad status. Before the patch,
>> we'd just wait sitting on the channel for HZ/5 (200ms) before trying
>> again, with the patch we immediately retransmit the packet, which will
>> fail again and again until the firmware received a beacon.
>>
>> If you look at iwlwifi/dvm/, it has some passive_no_rx workaround for
>> this, which I don't see in iwlegacy.
>
> Can you explain why it is named passive_no_rx instead passive_no_tx ?

Well, it is basically - passive channel with no rx :-) This means we can't tx.

>> I think the best way to solve this would be to do such a thing in
>> iwlegacy as well, but until then and for stable maybe we should
>> introduce another HW flag to restore the previous mac80211 behaviour?
>
> I'm not sure if I like to add passive_no_rx to iwlegacy. Stopping queues
> and waiting for beacon looks sticky, what happen if beacon will not be
> received?
>
> Perhaps I will just remove IEEE80211_HW_REPORTS_TX_ACK_STATUS from 4965,
> it's simpler workaround ?
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