Message-ID: <5139B35D.9060803@neratec.com> (sfid-20130308_105155_943166_3F0842C9)
Date: Fri, 08 Mar 2013 10:46:05 +0100
From: Wojciech Dubowik <Wojciech.Dubowik@neratec.com>
MIME-Version: 1.0
To: Felix Fietkau <nbd@openwrt.org>
CC: linux-wireless@vger.kernel.org, linville@tuxdriver.com,
	mcgrof@qca.qualcomm.com
Subject: Re: [PATCH 3.8 1/3] ath9k_hw: fix calibration issues on chainmask
 that don't include chain 0
References: <1358715322-46447-1-git-send-email-nbd@openwrt.org> <5138A4C8.7040500@neratec.com> <5138AB4A.7000405@openwrt.org> <5138B656.5090408@neratec.com> <513996DE.6030500@neratec.com>
In-Reply-To: <513996DE.6030500@neratec.com>
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Sender: linux-wireless-owner@vger.kernel.org

On 03/08/2013 08:44 AM, Wojciech Dubowik wrote:
> On 03/07/2013 04:46 PM, Wojciech Dubowik wrote:
>> On 03/07/2013 03:59 PM, Felix Fietkau wrote:
>>> On 2013-03-07 3:31 PM, Wojciech Dubowik wrote:
>>>> There is a regression introduced by this patch when power save is 
>>>> off on
>>>> the station for idle checks.
>>>> I have AR9590 station with rx and tx chain set to 0x1 connected
>>>> to legacy AP (based on Ar9390) with RF cable and 40dB attenuator.
>>>>
>>>> Before this patch in connection polling the station was properly 
>>>> sending
>>>> null function to check whether AP is still there. After this patch 
>>>> it sends
>>>> broadcast probe request which is anyway wrong or some 16 or so packets
>>>> of random data (rarely). It manifests itself in lost connection 
>>>> because
>>>> there
>>>> is no ack from AP which is expected for null function.
>>>>
>>>> I have been following skb's up to the descriptor setting in ath9k 
>>>> and it was
>>>> all ok i.e. proper null function with valid addresses.
>>>>
>>>> I have been bisecting it twice because it doesn't make much sense 
>>>> but maybe
>>>> it's a HW issue?
>>> You're right, it does not make much sense. I can't figure out how this
>>> patch could possibly change the runtime behavior with tx chainmask set
>>> to 0x1. Have you tried reverting this patch in a current build to 
>>> see if
>>> that fixes the issue?
>> It does fix it. I will check tomorrow whether it's only AR9590 or also
>> previous revisions. I will also try with different chainmasks. I will 
>> have
>> to rescrew my setup...
>>
> I have been doing some tests and it seems to affect both AR9390 and 
> AR9590.
> To summarize: sta doesn't send null function but broadcast probe 
> request or
> corrupted frames in idle checking routine when power save is off and 
> only some
> antennas are selected for transmission.
> So for example when I set antenna mask 7 i.e. all available it works 
> ok but with
> mask 1, 3 or 6 not. When I swith power save it's all ok no matter what 
> mask I use.
>
> Thing with power save on is that before it goes to idle check it will 
> go to sleep since
> there is no traffic anyway, then we get beacon miss, it wakes up and 
> it sends null
> function. I guess waking up is reinitializing sth in a chip which 
> doesn't occur in my
> scenario.
> HW issue?
It will also work if I set user specified antenna masks instead of hw 
capabilities.
Shouldn't it be the case anyway?

Wojtek