Date: Wed, 2 Jul 2014 10:30:03 -0400
From: "John W. Linville" <linville@tuxdriver.com>
To: "Luis R. Rodriguez" <mcgrof@suse.com>
Cc: linux-wireless@vger.kernel.org,
	Johannes Berg <johannes@sipsolutions.net>,
	Janusz Dziedzic <janusz.dziedzic@tieto.com>,
	Ming Lei <ming.lei@canonical.com>, Takashi Iwai <tiwai@suse.de>
Subject: Re: [PATCH] wireless: fixup genregdb.awk for remove of antenna gain
 from wireless-regdb
Message-ID: <20140702143003.GA13564@tuxdriver.com> (sfid-20140702_163024_314261_33BB4C6E)
References: <1404245874-350-1-git-send-email-linville@tuxdriver.com>
 <20140702001936.GQ27687@wotan.suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
In-Reply-To: <20140702001936.GQ27687@wotan.suse.de>
Sender: linux-wireless-owner@vger.kernel.org

On Wed, Jul 02, 2014 at 02:19:36AM +0200, Luis R. Rodriguez wrote:
> On Tue, Jul 01, 2014 at 04:17:54PM -0400, John W. Linville wrote:
> > Since "wireless-regdb: remove antenna gain" was merged in the
> > wireless-regdb tree, this script has been incompatible with the
> > 'official' regulatory database.  Let's fix it up.
> > 
> > Signed-off-by: John W. Linville <linville@tuxdriver.com>
> > ---
> > I think the dfs_cac stuff is still broken, since it does not account
> > for the starting offset of the flags.
> 
> Indeed, but that also breaks other stuff too, because the DFS CAC stuff
> is optional it means the flags can now start at different locations, it
> also means that we need to distinguish a flag from a CAC. 
> 
> Here's a complex example we should test for as an example now:
> 
> country US: DFS-FCC
> 	(2400 - 2450 @ 40), (100 mW)
> 	(2450 - 2500 @ 0), (100 mW), DFS, AUTO-BW
> 	(5170 - 5250 @ 80), (100 mW), DFS, AUTO-BW, NO-OUTDOOR
> 	(5250 - 5330 @ 0), (20), (60000), DFS, AUTO-BW
> 	(5735 - 5835 @ 80), (30)
> 	(57240 - 63720 @ 2160), (40)
> 
> The changes below seem to address it. I think awk is too fragile to

Your patch looks almost exactly like what I was thinkg to do.

> scale well and keep us sane. A C parser exists but right now it
> ignores the DFS CAC. Having a parser is nice as it allows us to
> modify the db.txt on the fly, however parser still requires a bit
> of an update in code. If we wanted to avoid the parser all together
> we could just merge a CRDA reader at build time and require a
> a regulatory.bin file for reading instead of the db.txt. If we
> had support for that then its really only one step further from
> having full CRDA functionality upstream on the kernel, ie letting
> us read the file at run time rather than just build time. If we
> are to follow the steps from udev with its firmware loader helper
> we might as well merge CRDA upstream, in fact we could just use
> request_firmware_direct() for the reader, what remains questionable
> to me is the signing stuff, but if we already have support module
> signing checks it doesn't seem far fetched to be able to have
> request firmware verify a signature on a file, which probably
> ain't such a bad idea anyway. If we did this we'd have two options:
> 
> 1) regulatory.bin reader at build time to build the static regulatory domains
> 2) the same reader code can use request the file at run time via
>    request_firmware_direct() and if we added signature verification
>    it can replace CRDA
> 
> We'd eliminate the ASCII representation completely from the build picture
> and peg a regulatory.bin firmware to each kernel then. Thoughts?

I'll have to digest this -- needs some more discussion, for sure.

> diff --git a/net/wireless/genregdb.awk b/net/wireless/genregdb.awk
> index 40c37fc..baf2426 100644
> --- a/net/wireless/genregdb.awk
> +++ b/net/wireless/genregdb.awk
> @@ -51,32 +51,41 @@ function parse_country_head() {
>  
>  function parse_reg_rule()
>  {
> +	flag_starts_at = 7
> +
>  	start = $1
>  	sub(/\(/, "", start)
>  	end = $3
>  	bw = $5
>  	sub(/\),/, "", bw)
> -	gain = $6
> -	sub(/\(/, "", gain)
> -	sub(/,/, "", gain)
> -	power = $7
> -	sub(/\)/, "", power)
> -	sub(/,/, "", power)
> +	gain = 0
> +	power = $6
>  	# power might be in mW...
> -	units = $8
> +	units = $7
> +	dfs_cac = 0
> +
> +	sub(/\(/, "", power)
> +	sub(/\),/, "", power)
> +	sub(/\),/, "", units)
>  	sub(/\)/, "", units)
> -	sub(/,/, "", units)
> -	dfs_cac = $9
> +
>  	if (units == "mW") {
> +		flag_starts_at = 8
>  		power = 10 * log(power)/log(10)
> +		if ($8 ~ /[[:digit:]]/) {
> +			flag_starts_at = 9
> +			dfs_cac = $8
> +		}
>  	} else {
> -		dfs_cac = $8
> +		if ($7 ~ /[[:digit:]]/) {
> +			flag_starts_at = 8
> +			dfs_cac = $7
> +		}
>  	}
> -	sub(/,/, "", dfs_cac)
>  	sub(/\(/, "", dfs_cac)
> -	sub(/\)/, "", dfs_cac)
> +	sub(/\),/, "", dfs_cac)
>  	flagstr = ""
> -	for (i=8; i<=NF; i++)
> +	for (i=flag_starts_at; i<=NF; i++)
>  		flagstr = flagstr $i
>  	split(flagstr, flagarray, ",")
>  	flags = ""
> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.