On Feb 1, 2008 4:45 PM, Luis R. Rodriguez <mcgrof@xxxxxxxxxxxxxxxxxx> wrote:
> On Feb 1, 2008 1:47 PM, Nick Kossifidis <mickflemm@xxxxxxxxx> wrote:
> > 2008/2/1, Luis R. Rodriguez <mcgrof@xxxxxxxxxxxxxxxxxx>:
> >
> > > 2008/2/1 Johannes Berg <johannes@xxxxxxxxxxxxxxxx>:
> > > >
> > > > > > What is cap_range and why should it be in struct wiphy?
> > > > >
> > > > > Its the device's frequency capability range on the bands.
> > > >
> > > > Well since we always need channels I decided to not have such a thing
> > > > but rather require registering a channels array that is also used for
> > > > bookkeeping about enabled/disabled channels etc.
> > > >
> > > > I guess you could add a helper function that allocates a channels array
> > > > based on a frequency range.
> > >
> > > This is true but also it would be nice as it is the end points which
> > > drivers may want
> > > to access every now and then. I think its worth the few bytes.
> > >
> > > Luis
> >
> > Why mac80211/cfg80211 has to know about phy's channel range ? I mean
> > driver knows it and that's all we need to create the big (unfiltered)
> > channel array.
>
> Yes, you are right, from a driver's perspective this is all we need
> this for. But, for example, say user tries to change to a channel by
> freq, and we want to see if we support it, wouldn't it be easier to
> have mac80211 do the check for us against the wiphy's range on the
> band instead of having the driver do it? mac80211 would do it a lot
> quicker by just knowing the range for example.
>
> > These caps are set for some chip revisions (eg. 5210
> > supports only part of 5GHz band while 5111/5112 support much wider
> > range) and only used by channel_ok during channel setup (attach), we
> > don't have any other use for those inside the driver.
>
> Sure.
>
> > Other drivers
> > don't even need such caps because channel ranges are standard for all
> > their chip revisions, or they get channels from firmware, or use fixed
> > range/channel table no matter what phy supports etc.
>
> I just want to make it available for drivers in central place for
> those who *could* use it and for mac80211 for a quick short cut.
> Additionally it seems it would be good to export this to userspace
> instead of having it iterate over the array to simply get the range.
>
> > The only use i can imagine for frequency range information on
> > mac80211/cfg80211 is that the whole channel setup is being done during
> > wiphy setup (we provide frequency range and supported bands and
> > mac80211/cfg80211 does the rest) but we'll have (at least for ath5k)
> > to fill channel flags (hw_value) anyway.
>
> You are right, we discussed this a while back on the list as well and
> came to the same conclusion. I am curious -- are there drivers which
> have the same hw_value as the freq? But disregard this -- this isn't
> the reason why I brought up the cap. I've mentioned the reasons above
> and to johill in my last reply. Please let me know what you think.
>
> > About the patch: You are right that we should use channel_ok in
> > hw_channel but there is no need for that switch, channel_ok checks the
> > channel flags (hw_value) and determines the band already (and channel
> > flags are filled per band -CHANNEL_2GHZ/CHANNEL_5GHZ- during setup so
> > checking channel->band or channel->hw_vallue is the same).
>
> OK I think I see your point. I can send a follow up patch if you don't mind.
I'm just going to resend all pending patches. For this stuff I've
shifted a bit like this:
/*
* Check bounds supported by the PHY (we don't care about regultory
* restrictions at this point). Note: hw_value already has the band
* (CHANNEL_2GHZ, or CHANNEL_5GHZ) so we inform ath5k_channel_ok()
* of the band by that */
if (!ath5k_channel_ok(ah, channel->center_freq, channel->hw_value)) {
char bname[5];
switch (channel->band) {
case IEEE80211_BAND_2GHZ:
strcpy(bname, "2 GHz");
break;
case IEEE80211_BAND_5GHZ:
strcpy(bname, "5 GHz");
break;
default:
BUG_ON(1);
return -EINVAL;
}
ATH5K_ERR(ah->ah_sc,
"channel frequency (%u MHz) out of supported "
"%s band range (%u - %u MHz)\n",
channel->center_freq,
bname,
ah->ah_capabilities.cap_range.range_2ghz_min,
ah->ah_capabilities.cap_range.range_2ghz_max);
return -EINVAL;
}
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