> Hi
>
> 2016-01-26 3:28 GMT-05:00 Grumbach, Emmanuel
> <emmanuel.grumbach@xxxxxxxxx>:
> >
> >
> > On 01/26/2016 12:20 AM, Nikolay Martynov wrote:
> >> It looks like sometimes firmware returns zero for chain noise and
> >> signal during calibration period. This seems to be a known problem
> >> and current implementation accounts for this by ignoring invalid data
> >> when all chains return zero signal and noise.
> >>
> >> The problem is that sometimes firmware returns zero for only one
> >> chain for some (not all) beacons used for calibration. This leads to
> >> perfectly valid chains be disabled and may cause invalid gain settings.
> >> For example this is calibration data taken on laptop with Intel 6300
> >> card with all three antennas attached:
> >>
> >> active_chains: 3
> >> chain_noise_a: 312
> >> chain_noise_b: 297
> >> chain_noise_c: 0
> >> chain_signal_a: 549
> >> chain_signal_b: 513
> >> chain_signal_c: 0
> >> beacon_count: 16
> >> disconn_array: 0 0 1
> >> delta_gain_code: 4 0 0
> >> radio_write: 1
> >> state: 3
> >>
> >> This patch changes statistics gathering to make sure that zero noise
> >> results are ignored for valid rx chains. The rationale being that
> >> even if anntenna is not connected we should be able to see non zero
> >> noise if rx chain is present.
> >
> > But then the firmware will continue to send zero for signal and this
> > will impact lots of flows like roaming. If the driver allows the
> > firmware to use that antenna, the firmware may use this antenna for
> > scanning and roaming will be broken.
> > This seems to be a bug in the firmware, but there isn't much I can do
> > about it.
> > Sorry, I have to NACK this patch.
>
> Could you please elaborate on how this patch would affect roaming or other
> things. As far as I can see this patch doesn't change much behavior apart
> from ignoring invalid values from firmware.
> Disconnected antennas still get disabled (as before) connected antennas still
> work (more often than before). So I'm not sure I can see how this patch
> would change what firmware does at all. I really hope you could find a
> moment and explain this.
>
What you are saying here is that there is a bug in the firmware which makes it report wrong
values for one of the antennas. But when you will have this antenna enabled (with your patch),
the firmware will keep sending bad signal / noise values for it. If the driver allows the firmware
to use this antenna (after your patch), the firmware will choose this antenna to receive beacons
or to scan. Then, the driver will look at the beacons' rssi (which will be wrong) and it will think that
an AP which is very close is in fact far away.
��.n��������+%������w��{.n�����{���zW����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
