RE: [ipw3945-devel] IWL3945 always reports noise levels of -127

Cahill, Ben M
2009-05-05T18:45:34Z

Excellent information. Thank you.

We just issued new 3945 uCode within the past week or two ... Is that also showing the problem (noise_diff = 0)?

-- Ben --

>-----Original Message-----
>From: Maxim Levitsky [mailto:maximlevitsky@gmail.com]
>Sent: Tuesday, May 05, 2009 12:17 PM
>To: Cahill, Ben M
>Cc: iwlwifi maling list; linux-wireless
>Subject: RE: [ipw3945-devel] IWL3945 always reports noise
>levels of -127
>
>On Tue, 2009-05-05 at 17:50 +0300, Maxim Levitsky wrote:
>> On Mon, 2009-05-04 at 12:27 -0700, Cahill, Ben M wrote:
>> >
>> > >-----Original Message-----
>> > >From: Maxim Levitsky [mailto:maximlevitsky@gmail.com]
>> > >Sent: Monday, May 04, 2009 3:04 PM
>> > >To: Cahill, Ben M
>> > >Cc: iwlwifi maling list; linux-wireless
>> > >Subject: RE: [ipw3945-devel] IWL3945 always reports noise
>> > >levels of -127
>> > >
>> > >On Mon, 2009-05-04 at 11:53 -0700, Cahill, Ben M wrote:
>> > >> When one of our devices cannot figure out what the actual
>> > >noise level is, it reports -127.
>> > >>
>> > >> Newer devices are better at old devices at figuring noise
>> > >level. IIRC, 3945 cannot figure noise for CCK signals, and
>> > >may not be possible with OFDM as well.
>> > >
>> > >Why then it did work on older kernel ?
>> > >(and noise levels seemed to be correct)
>> >
>> > Hmmm, good point, and I don't know the answer! :-(
>> >
>>
>> And I do know it now (this is what I suspected...)
>> This is firmware issue.
>>
>> I forced the driver to use older firmware iwlwifi-3945-1.ucode,
>> and noise levels are back.
>
>
>Indeed old microcode reports values like that:
>rssi:017 agc:000 sig_avg:5437 noise_diff:580
>
>
>New microcode reports this instead:
>rssi:018 agc:000 sig_avg:140 noise_diff:000
>
>
>noise_diff is always zero now, and range for sig_avg changed.
>
>I also noticed that with older firmware I couldn't set the tx speed
>Thus what recently fixed it was a firmware update!
>(But in both cases OFDM rated were used)
>
>Thats all nothing to debug any more here.
>
>
>Best regards,
> Maxim Levitsky
>
>