[PATCH] ieee80211: Output frequency rather than channel in scan results

[PATCH] ieee80211: Output frequency rather than channel in scan results

[Larry Finger]

In ieee80211, the output of scan results lists channels rather than
frequencies; however, NetworkManager needs frequency. This patch
changes the output from channel to frequency.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
---

Index: wireless-2.6/net/ieee80211/ieee80211_wx.c
===================================================================
--- wireless-2.6.orig/net/ieee80211/ieee80211_wx.c
+++ wireless-2.6/net/ieee80211/ieee80211_wx.c
@@ -89,12 +89,15 @@ static char *ieee80211_translate_scan(st
 		start = iwe_stream_add_event(start, stop, &iwe, IW_EV_UINT_LEN);
 	}
 
-	/* Add frequency/channel */
+	/* Add frequency */
 	iwe.cmd = SIOCGIWFREQ;
-/*	iwe.u.freq.m = ieee80211_frequency(network->channel, network->mode);
-	iwe.u.freq.e = 3; */
-	iwe.u.freq.m = network->channel;
-	iwe.u.freq.e = 0;
+	if (network->channel < 15)
+		iwe.u.freq.m = 2407 + 5 * network->channel;
+	else
+		iwe.u.freq.m = 5000 + 5 * network->channel;
+	if (network->channel == 14)
+		iwe.u.freq.m = 2484;    /* special case for Japan */
+	iwe.u.freq.e = 6;
 	iwe.u.freq.i = 0;
 	start = iwe_stream_add_event(start, stop, &iwe, IW_EV_FREQ_LEN);
 

Re: [PATCH] ieee80211: Output frequency rather than channel in scan results

[Pavel Roskin]

Quoting Larry Finger <Larry.Finger@lwfinger.net>:

> In ieee80211, the output of scan results lists channels rather than
> frequencies; however, NetworkManager needs frequency. This patch
> changes the output from channel to frequency.

The driver can report both, and I think it should.  This would make the iwlist
output a bit longer, but kernel drivers shouldn't be written to make userspace
program generate pretty output.

--
Regards,
Pavel Roskin

Re: [PATCH] ieee80211: Output frequency rather than channel in scan results

[Dan Williams]

On Sat, 2007-04-21 at 00:12 -0400, Pavel Roskin wrote:
> Quoting Larry Finger <Larry.Finger@lwfinger.net>:
> 
> > In ieee80211, the output of scan results lists channels rather than
> > frequencies; however, NetworkManager needs frequency. This patch
> > changes the output from channel to frequency.
> 
> The driver can report both, and I think it should.  This would make the iwlist
> output a bit longer, but kernel drivers shouldn't be written to make userspace
> program generate pretty output.

I'm trying to remember why NM cares about frequency, and I think it's
for ad-hoc mode; but wpa_supplicant didn't historically support a
"channel" configuration parameter and so you can't create adhoc networks
with NM right now anyway...  What's the failure mode?

Dan

> --
> Regards,
> Pavel Roskin
> -
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Re: [PATCH] ieee80211: Output frequency rather than channel in scan results

[Larry Finger]

Dan Williams wrote:
> On Sat, 2007-04-21 at 00:12 -0400, Pavel Roskin wrote:
>> Quoting Larry Finger <Larry.Finger@lwfinger.net>:
>>
>>> In ieee80211, the output of scan results lists channels rather than
>>> frequencies; however, NetworkManager needs frequency. This patch
>>> changes the output from channel to frequency.
>> The driver can report both, and I think it should.  This would make the iwlist
>> output a bit longer, but kernel drivers shouldn't be written to make userspace
>> program generate pretty output.
> 
> I'm trying to remember why NM cares about frequency, and I think it's
> for ad-hoc mode; but wpa_supplicant didn't historically support a
> "channel" configuration parameter and so you can't create adhoc networks
> with NM right now anyway...  What's the failure mode?

In the KDE NM applet, the frequency is listed as 0.

Larry

Re: [PATCH] ieee80211: Output frequency rather than channel in scan results

[Dan Williams]

On Sat, 2007-04-21 at 17:55 -0500, Larry Finger wrote:
> Dan Williams wrote:
> > On Sat, 2007-04-21 at 00:12 -0400, Pavel Roskin wrote:
> >> Quoting Larry Finger <Larry.Finger@lwfinger.net>:
> >>
> >>> In ieee80211, the output of scan results lists channels rather than
> >>> frequencies; however, NetworkManager needs frequency. This patch
> >>> changes the output from channel to frequency.
> >> The driver can report both, and I think it should.  This would make the iwlist
> >> output a bit longer, but kernel drivers shouldn't be written to make userspace
> >> program generate pretty output.
> > 
> > I'm trying to remember why NM cares about frequency, and I think it's
> > for ad-hoc mode; but wpa_supplicant didn't historically support a
> > "channel" configuration parameter and so you can't create adhoc networks
> > with NM right now anyway...  What's the failure mode?
> 
> In the KDE NM applet, the frequency is listed as 0.

Haha.  Ok.  NM should be smarter about this and convert channels
returned by the driver into frequencies.  In the end, I prefer
frequencies where at all possible, because channel numbers are _not_
unique (unless you use the the tuple of [standard, band, channel] where
standard is something like "802.11" or "802.16", band is "a" or "bg").

Dan


Dan

Re: [PATCH] ieee80211: Output frequency rather than channel in scan results

[Larry Finger]

Dan Williams wrote:
> 
> Haha.  Ok.  NM should be smarter about this and convert channels
> returned by the driver into frequencies.  In the end, I prefer
> frequencies where at all possible, because channel numbers are _not_
> unique (unless you use the the tuple of [standard, band, channel] where
> standard is something like "802.11" or "802.16", band is "a" or "bg").

My current (but not yet accepted) patch for ieee80211 outputs both channel and frequency as does the 
"soon to be submitted" one for mac80211. I agree that frequency is unique; however, I find it easier 
to think in terms of channels. In addition, I only use the bg band and have no confusion. If both 
are listed, everyone should be happy.

Larry