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From: "Nikita N." <nikitan@operamail.com>
To: brcm80211-dev-list@broadcom.com, linux-wireless@vger.kernel.org,
	arend@broadcom.com
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Subject: BCM4313 lowering TX power
Date: Sun, 15 Feb 2015 05:32:16 -0800
Sender: linux-wireless-owner@vger.kernel.org
List-ID: <linux-wireless.vger.kernel.org>

Hi Dear backports Devs for driver brcmsmac,
Coming to the point, I want to lower the TX power of my BCM4313, under
the official values set by the regdom, to any special value I need.
So I'm trying to build such a "personal" patch, only for me, based on
latest backports v3.19 and latest Ubuntu.
Useless to say, "iwconfig <wlan> txpower" doesn't work, the resulting TX
power doesn't change.
I know it doesn't work because I can measure the RSSI coming out from
the BCM4313, using another device: it doesn't change, whatever value I
set.

So, I gave a look at the code for the brcmsmac module, and I think I
found the location where the TX power is *finally* set: inside
wlc_lcnphy_txpower_recalc_target (phy_lcn.c), call to
wlc_lcnphy_set_target_tx_pwr.
AFAIU, in that function a table of tx_power_offsets (calculated by
another function) is written in the device EPROM registry, and the TX
power is set to the relative minimum.

Now, my question: is that the right way to change effectively the TX
power?
I need to ask You a confirmation about that, if that is correct, before
I start building my patch.
I don't want to frustrate my time developing in the wrong code, or
damage the device, or other issues... :)

Thank you for your attention, and looking forward your feedback.

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