From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Berg <johannes@sipsolutions.net>
Date: Thu, 23 May 2013 23:33:59 +0200
Subject: [ath9k-devel] [PATCH v3 1/3] mac80211: add STBC flag for
	radiotap
In-Reply-To: <1369318279-13768-1-git-send-email-linux@rempel-privat.de>
	(sfid-20130523_161134_412220_27EEFD62)
References: <1369250674.8207.26.camel@jlt4.sipsolutions.net>
	<1369318279-13768-1-git-send-email-linux@rempel-privat.de>
	(sfid-20130523_161134_412220_27EEFD62)
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On Thu, 2013-05-23 at 16:11 +0200, Oleksij Rempel wrote:

> -		*pos++ = local->hw.radiotap_mcs_details;
> +
> +		/* MCS known field */
> +		*pos = local->hw.radiotap_mcs_details;
> +		if (stbc)
> +			*pos |= IEEE80211_RADIOTAP_MCS_HAVE_STBC;

I think you shouldn't make this change, and the driver should include
the HAVE_STBC flag in the hw.radiotap_mcs_details. I actually thought of
this approach as well, but now just realized that this means that if the
driver _knows_ that a certain frame was received w/o STBC, this
knowledge cannot be transferred to the user, which would be a loss of
information.

> +               if (stbc)
> +                       *pos |= (stbc >> RX_FLAG_STBC_SHIFT)
> +                                       <<
> IEEE80211_RADIOTAP_MCS_STBC_SHIFT;

No need for the if() here, OR'ing in 0 doesn't do anything.

johannes