On Sat, 2009-02-21 at 14:04 -0600, Larry Finger wrote: > Dan Williams wrote: > > On Sat, 2009-02-21 at 09:09 -0600, Larry Finger wrote: > >> I admit that I didn't follow the discussion of reporting signal quality very > >> closely; however since commit 708c57cf1709fb95, all of my wireless devices (b43, > >> p54usb, rtl8187) are reporting link quality as XX/70 rather than XX/100. I doubt > >> that this was an intended consequence of that patch. If the SIOCGIWRANGE ioctl > >> is now more correct, what changes are needed in the drivers to restore the old > >> behavior? Having written the qual calculation for 2 drivers, I understand the > >> uselessness of this number, but I also know the uproar such a change will cause > >> in the user community. > > > > Intended. It doesn't matter what the /X number is; it's simply the > > upper bound of what the # before the / will be. Quality is in the range > > of [0 ... max_qual.qual]. You should be able to divide quality / > > max_qual.qual and get a reasonable number to use for pretty UI display. > > > > Many drivers used to use something other than 100 for max quality, and > > many still do: > > > > airo.c: range->max_qual.qual = airo_get_max_quality(&cap_rid); > > hostap/hostap_ioctl.c: range->max_qual.qual = 70; /* what is correct max? This was not > > hostap/hostap_ioctl.c: range->max_qual.qual = 92; /* 0 .. 92 */ > > netwave_cs.c: range->max_qual.qual = 255; > > orinoco/wext.c: range->max_qual.qual = 0x8b - 0x2f; > > wavelan.c: range->max_qual.qual = MMR_SGNL_QUAL; > > wavelan_cs.c: range->max_qual.qual = MMR_SGNL_QUAL; > > zd1201.c: range->max_qual.qual = 128; > > I know how it works with drivers that implement their own ioctl calls for the > WEXT interface; however, the 3 that I mentioned all use mac80211 and get their > WEXT support through cfg80211. It's not really relevant what mac80211/cfg80211 uses for max_qual.qual. What's relevant is that the calculation that the driver/stack makes for quality is appropriate for the max_qual.qual. Again, it doesn't matter what the /XX number is, as long as you can take YY/XX and get something between 0 and 100 (inclusive) that changes on a linear scale and is usable for a generic "signal strength %" measure. Dan -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
