netdev - Re: 2.6.33.2: Turn tx power off/on for Atheros card

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Date:	Thu, 6 May 2010 15:16:48 -0700
From:	"Luis R. Rodriguez" <mcgrof@...il.com>
To:	Yegor Yefremov <yegorslists@...glemail.com>
Cc:	linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: 2.6.33.2: Turn tx power off/on for Atheros card

On Thu, May 6, 2010 at 7:52 AM, Yegor Yefremov
<yegorslists@...glemail.com> wrote:
> On Wed, May 5, 2010 at 12:26 PM, Yegor Yefremov
> <yegorslists@...glemail.com> wrote:
>> I'm using kernel 2.6.33.2 with AR2413 WLAN card. Issuing
>>
>> iwconfig wlan0 txpower off
>>
>> turns txpower off. I can see this status by iwconfig wlan0 and the
>> communication with AP terminates. But when I turn the txpower on
>>
>> iwconfig wlan0 txpower on
>>
>> nothing happens. Though iwconfig shows the previous tx power value.
>> Only ifconfig wlan0 down and then up recovers the transmission.
>>
>> Is it a known bug or I'm doing something wrong?
>
> I made some debugging and found out that after iwconfig wlan0 txpower
> off dev_close() will be invoked, so that local->open_count will be 0.
> The next time txpower on will be called, it will be checked if
> local->open_count > 0 and this conditions fails, so no  hardware
> configuration will be made.
>
> I've made a quick and dirty hack, that opens the wireless device by
> enabling the txpower, if it was closed before. Is there any proper
> solution? Is it really necessary to close device to tunr txpower off?

Depends on the type of interfaces you have. For a monitor device it
makes no sense to close the device as you should be able to still RX.
It also is possible to TX over a monitor device using frame injection
so technically setting tx power to off would just mute it and would
seem useful.

  Luis
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