Subject: Re: New Regulatory Domain Api.
From: Zhu Yi <yi.zhu@intel.com>
To: Marcel Holtmann <holtmann@linux.intel.com>
Cc: "Luis R. Rodriguez" <lrodriguez@atheros.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Luis Rodriguez <Luis.Rodriguez@atheros.com>,
	Tomas Winkler <tomasw@gmail.com>,
	"John W. Linville" <linville@tuxdriver.com>,
	"Kolekar, Abhijeet" <abhijeet.kolekar@intel.com>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
In-Reply-To: <1224520999.9386.72.camel@californication>
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Date: Tue, 21 Oct 2008 09:34:59 +0800
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On Mon, 2008-10-20 at 10:43 -0600, Marcel Holtmann wrote:
> I do wanna keep it as simple as possible, but on the other hand we
> should do a pretty decent job with picking a regulatory domain when no
> userspace is present (old or CRDA missing).
> 
> So my current thinking is that the regulatory hint for a card is limited
> to the frequencies the card actually registers with mac80211. If the
> internal card is 2.4 GHz, then we limit the hint to this. So the 5 GHz
> band is still a virgin. If a 5 GHz card comes along and it is the first
> in its band, then we take its regulatory hint for that band, but for the
> 2.4 GHz band it has to follow the first cards hint.
> 
> As I mentioned before, first card wins is a perfect solution from my
> point of view, but we should not punish a second card in a different
> band if the first card is not touching this band at all. And I can see
> these user scenarios happening and in some cases they might be done on
> purpose to serve every band with a different piece of hardware.
> 
> And for the cases where new bands might be used in the future. In that
> case we do have to do this right since userspace might be outdated. Lets
> face it, we should always support a new kernel with an old userspace.
> That is how the Linux kernel is suppose to work. That is probably the
> only reason why wireless extensions are still around ;)
> 
> The idea of having a 2.4 GHz only card provide a hint for 5 GHz is just
> plain wrong. If the hardware is designed for 2.4 GHz it should not mess
> with other frequencies.
> 
> So my solution would be first regulatory hint in each band wins.
> 
> Also we should have printk that shows up in dmesg in cases where neither
> crda or iw modified the regulatory domain and we have clash with the
> hints provided by two or more cards.

I totally agree with you. IIRC, the current situation is nobody is
willing to implement the per-band regulatory hints for such a rare but
valid case. Luis, will you accept patches if somebody else write it?

Thanks,
-yi