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From: Julius Schulz-Zander <julius@net.t-labs.tu-berlin.de>
Subject: Re: [ath9k-devel] ath9k: Deaf QCA9558 when setting rxchainmask
Date: Sat, 9 Nov 2013 01:32:25 +0100
To: Sven Eckelmann <sven@open-mesh.com>
Sender: linux-wireless-owner@vger.kernel.org

Hi Sven,

I've asked nbd about this some time ago. It doesn't work if you have gaps in the chain mask! Try chain mask 3 (110) and it should work with 2x2.

Regards,
 -Julius

On 06.11.2013, at 16:04, Sven Eckelmann <sven@open-mesh.com> wrote:

> Hi,
> 
> I've needed to test some problems with a QCA9558 Rev 0 based 3x3 2.4G device. 
> During these tests I've wanted to try different antenna configurations to 
> reduce the complexity of the problem. This was done by setting the 
> rxchainmask/txchainsmask to settings like 1, 5 and 7. Unfortunatelly, the 
> setting 5 (antenna 0 and 1) turned the device completely deaf. Here an 
> overview of the settings (excerpt)
> 
> chainmask | ant 0 | ant 1 | ant 2 | Status
> 1         | 1     | 0     | 0     | works
> 5         | 1     | 0     | 1     | deaf
> 7         | 1     | 1     | 1     | works
> 
> The antenna setting is used in ath9k at different places but trigger seems to 
> be the AR_PHY_RX_CHAINMASK register write in ar9003_phy.c in the function 
> ar9003_hw_set_chain_masks. Forcing it to 7 instead of the requested 5 avoids 
> this deaf state (but makes the rx chainmask setting useless). Of course, this 
> is not a valid workaround and quite unexpected.
> 
> The test platform was a current trunk OpenWrt build together with compat-
> wireless 2013-02-22, compat-wireless 2013-06-27 and backports 2013-10-31. The 
> settings were configured using the txantenna and rxantenna of the OpenWrt 
> wireless config system. Both were always set to the same values during the 
> tests.
> 
> The deaf state was identified using 1x1 and 2x2 clients which could receive 
> the beacons of the device. The QCA9558 device was then unable to receive the 
> probe request from the clients or any other traffic on the air. This was also 
> checked by a monitor (flags: control) interface on the same phy.
> 
> Maybe someone knows whether this is a known problem with this SoC or what 
> information can be gathered to debug this problem further.
> 
> Kind regards,
>    Sven
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