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

Maxim Levitsky
2009-05-05T16:16:37Z

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,