Re: Signal quality strange since commit 708c57cf1709fb95

[Larry Finger <Larry.Finger@lwfinger.net>]

Johannes Berg wrote:
> On Mon, 2009-02-23 at 22:18 -0600, Larry Finger wrote:
> 
>> No, I just wondered if it was intentional that it was changed to /70. It appears
>> that it was, therefore, at least 3 drivers must be changed as they are
>> calculating on the basis of /100. For example, my b43 is showing an iwconfig
>> Link Quality of 93/70 while the KNM applet is showing 50%.
> 
> Well that _is_ a bug, since this shouldn't have required driver changes!
> I'll take a look into why that might be happening.

Drivers b43, b43legacy, rtl8187, and p54usb all assume a Link Quality scaled to
100, which was the behavior before the commit in the subject. I don't quite
understand why as the old code had this fragment:

-       if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
-               /*
-                * cfg80211 assumes -110 to -40 dBm and clamps to that range
-                * for qual.qual, so tell userspace this is what we give it
-                * but take into account that we have to start from 0.
-                */
-               range->max_qual.qual = 70;
-               range->avg_qual.qual = 35;
-       } else {
-               /*
-                * cfg80211 just uses the level value for qual too, and it
-                * requires the level value to be 0 .. 100.
-                */
-               range->max_qual.qual = 100;
-               range->avg_qual.qual = 50;
-       }

That should have set max_qual.qual to 70 as all the drivers set
IEEE80211_HW_SIGNAL_DBM. I don't know why, but the code took the other branch,
which seems to have been some other bug.

Larry