Unable to set txpower on wifi card

JD jd1008 at gmail.com
Mon Aug 30 17:54:47 UTC 2010


  On 08/30/2010 11:00 AM, Terry Polzin wrote:
> On Mon, 2010-08-30 at 10:41 -0700, JD wrote:
>> F13, latest updates.
>> wifi card: Sparklan wmir-200N
>> http://www.sparklan.com/product.php?func=view&prod_id=43
>> Chipset: RT2860/RT2850
>>
>> The Datasheet says:
>>
>> Output Power
>> 802.11a: 12.5dBm ± 1.5dBm
>> 802.11b: 17dBm ± 1.5dBm
>> 802.11g: 14dBm ± 1.5dBm
>> 802.11an: 14dBm ± 1.5dBm
>> 802.11gn: 14dBm ± 1.5dBm
>>
>> I am running in g mode (54megabits/s)
>>
>> $ sudo iwconfig wlan0
>> wlan0     IEEE 802.11abgn  ESSID:"Deleted"
>>             Mode:Managed  Frequency:2.462 GHz  Access Point:
>> aa:bb:cc:dd:ee:ff
>>             Bit Rate=54 Mb/s   Tx-Power=8 dBm<<<=====
>>             Retry  long limit:7   RTS thr:off   Fragment thr:off
>>             Encryption key:off
>>             Power Management:on
>>             Link Quality=70/70  Signal level=58 dBm
>>             Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
>>             Tx excessive retries:0  Invalid misc:0   Missed beacon:0
>>
>> I tried to set txpower to 14 per datasheet spec:
>>
>> $ sudo iwconfig wlan0 txpower 14dBm
>> Error for wireless request "Set Tx Power" (8B26) :
>>       SET failed on device wlan0 ; Invalid argument.
>>
>> The drivers that are loaded for this wifi card are:
>>
>> rt2800pci               7931  0
>> rt2800lib              27818  1 rt2800pci
>> rt2x00pci               5799  1 rt2800pci
>> rt2x00lib              25936  3 rt2800pci,rt2800lib,rt2x00pci
>> mac80211              182154  2 rt2x00pci,rt2x00lib
>> cfg80211              135626  2 rt2x00lib,mac80211
>> eeprom_93cx6            1305  1 rt2800pci
>> crc_ccitt               1311  2 rt2800pci,irda
>>
>> Is this an issue with the wext driver or with the rt2XXXXX drivers?
> Just for giggles, try the command as root, not sudoed from your mortal
> account.
>
What makes you think that would make a difference?
sudo works just fine for everything requiring root perms.
Furthermore, the error is complaining about the argument value.

Notice that if I specify the low value of 8, the command works just fine:

$ sudo iwconfig wlan0 txpower 8dBm
$

The driver does not comply with hardware specs.




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