[rt2x00-users] rt2800usb / RT3070L: setting txpower has no effect

Stanislaw Gruszka sgruszka at redhat.com
Mon Jul 16 20:56:16 AEST 2012


On Mon, Jun 25, 2012 at 10:38:46AM +0200, Roland Koebler wrote:
> > > I have now tracked down the change between compat-wireless-3.3 and 3.4
> > > which changed the txpower -- so, now I'm able to patch the source to
> > > modify the real transmitted power.
> > 
> > So which commit introduced the change?
> I don't know the commit, since I have compared the code of
> compat-wireless-3.3 and 3.4. But I'll post a patch as soon
> as it works as I expect.
> 
> > txpower control is not easy to
> > implement in rt2800 chipsets that don't have an EIRP calibration value
> > in their EEPROM (whcih most devices don't have).
> It may be hard to calculate the correct dBm values, but changing the
> txpower itself is easy (as soon as you know the code-structure of the
> wireless-drivers).
> 
> > > Or should this better be done by e.g. iwpriv? Is there any documentation
> > > how to add iwpriv-functions?
> > 
> > Both iwconfig and iwpriv are obsoleted by iw, see  [1].
> Thanks.

I'm going to post that patch, does it fix real tx power ?

Thanks
Stanislaw


>From b89aa1358d4e400b89eb414df73a7f6457f2f4b4 Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <sgruszka at redhat.com>
Date: Mon, 16 Jul 2012 12:47:41 +0200
Subject: [PATCH] wireless: reg: restore previous behaviour of chan->max_power calculations

commit eccc068e8e84c8fe997115629925e0422a98e4de
Author: Hong Wu <Hong.Wu at dspg.com>
Date:   Wed Jan 11 20:33:39 2012 +0200

    wireless: Save original maximum regulatory transmission power for the calucation of the local maximum transmit pow

changed the way we calculate chan->max_power as min(chan->max_power,
chan->max_reg_power). That broke rt2x00 (and perhaps some other
drivers) that do not set chan->max_power. It is not so easy to fix this
problem correctly in rt2x00.

According to commit eccc068e8 changelog, change claim only to save
maximum regulatory power - changing setting of chan->max_power was side
effect. This patch restore previous calculations of chan->max_power and
do not touch chan->max_reg_power.

Cc: stable at vger.kernel.org # 3.4+
Signed-off-by: Stanislaw Gruszka <sgruszka at redhat.com>
---
 net/wireless/reg.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index b2b3222..4a47878 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -894,7 +894,21 @@ static void handle_channel(struct wiphy *wiphy,
 	chan->max_antenna_gain = min(chan->orig_mag,
 		(int) MBI_TO_DBI(power_rule->max_antenna_gain));
 	chan->max_reg_power = (int) MBM_TO_DBM(power_rule->max_eirp);
-	chan->max_power = min(chan->max_power, chan->max_reg_power);
+	if (chan->orig_mpwr) {
+		/*
+		 * Devices that have their own custom regulatory domain
+		 * but also use WIPHY_FLAG_STRICT_REGULATORY will follow the
+		 * passed country IE power settings.
+		 */
+		if (initiator == NL80211_REGDOM_SET_BY_COUNTRY_IE &&
+		    wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY &&
+		    wiphy->flags & WIPHY_FLAG_STRICT_REGULATORY)
+			chan->max_power = chan->max_reg_power;
+		else
+			chan->max_power = min(chan->orig_mpwr,
+					      chan->max_reg_power);
+	} else
+		chan->max_power = chan->max_reg_power;
 }
 
 static void handle_band(struct wiphy *wiphy,
-- 
1.7.1




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