Re: Issue with ath9k and tx/rx chainmask: 3x3 doesn't work with mask of 0x1.

[Ben Greear <greearb@candelatech.com>]

On 08/22/2012 03:24 PM, Ben Greear wrote:
> On 08/22/2012 01:30 PM, Felix Fietkau wrote:
>> On 2012-08-20 10:24 PM, Ben Greear wrote:
>>> I am trying to test out an attenuator.  For now, I have only a single attenuator,
>>> so I set tx and rx chainmask to 0x1 on both AP and Station machine.
>>>
>>> I then connected channel 0 on the two machines together through the
>>> attenuator.
>>>
>>> I have two station interfaces on the station machine.  They both
>>> seem to associate OK, but they cannot receive dhcp responses.
>>>
>>> It *seems* that broadcast packets may go through fine.
>>>
>>> If I force the rate down to 1x1 or 2x2 MIMO (or force disable /n
>>> and just use /a), then it appears to work fine.
>>>
>>> Nics are WPEA-127n (AR9380).  Kernel is 3.5.1+ on AP, 3.5.2+ on station
>>> machine.
>>>
>>> I can see why forcing it down to 1x1 might work around some issue,
>>> but I find it funny that 2x2 works while 3x3 does not.
>> Did you set the chainmask manually via debugfs? If so, don't do that!
>> Use the nl80211 antenna control API (e.g. via iw)
>
> [root@lec2010-ath9k-1 lanforge]# ./local/sbin/iw phy wiphy0 set antenna 1 1
> command failed: Operation not supported (-95)
> [root@lec2010-ath9k-1 lanforge]# ./local/sbin/iw phy wiphy0 set antenna 1
> command failed: Operation not supported (-95)
> [root@lec2010-ath9k-1 lanforge]# ./local/sbin/iw phy wiphy0 set antenna 3
> command failed: Operation not supported (-95)
> [root@lec2010-ath9k-1 lanforge]# ./local/sbin/iw phy wiphy0 set antenna 7
> command failed: Operation not supported (-95)
> [root@lec2010-ath9k-1 lanforge]# uname -a
> Linux lec2010-ath9k-1 3.5.1+ #15 SMP PREEMPT Thu Aug 9 09:31:45 PDT 2012 i686 i686 i386 GNU/Linux

I'm guessing it is because of this:

static int ieee80211_set_antenna(struct wiphy *wiphy, u32 tx_ant, u32 rx_ant)
{
	struct ieee80211_local *local = wiphy_priv(wiphy);

	if (local->started)
		return -EOPNOTSUPP;

	return drv_set_antenna(local, tx_ant, rx_ant);
}


So, we'd have to admin down all virtual stations/aps/whatever before setting the
antenna configuration?

Thanks,
Ben


>
> # Set previously using debugfs.
> [root@lec2010-ath9k-1 lanforge]# cat /debug/ieee80211/wiphy0/ath9k/tx_chainmask
> 0x00000001
>
> [root@lec2010-ath9k-1 lanforge]# ./local/sbin/iw phy wiphy0 set antenna 7 7
> command failed: Operation not supported (-95)
>
>
> Any idea what I'm doing wrong?
>
> Thanks,
> Ben
>
>
>>
>> - Felix
>>
>
>


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com