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From:   Kalle Valo <kvalo@codeaurora.org>
To:     Brian Norris <briannorris@chromium.org>
Cc:     <linux-kernel@vger.kernel.org>,
        Amitkumar Karwar <amitkarwar@gmail.com>,
        Nishant Sarmukadam <nishants@marvell.com>,
        Ganapathi Bhat <gbhat@marvell.com>,
        Xinming Hu <huxinming820@gmail.com>,
        linux-wireless@vger.kernel.org
Subject: Re: [RFC PATCH v2 2/2] mwifiex: add NL80211_STA_INFO_RX_BITRATE support
References: <20181207001249.165477-1-briannorris@chromium.org>
        <20181207001249.165477-2-briannorris@chromium.org>
Date:   Fri, 07 Dec 2018 12:50:25 +0200
In-Reply-To: <20181207001249.165477-2-briannorris@chromium.org> (Brian
        Norris's message of "Thu, 6 Dec 2018 16:12:49 -0800")
Message-ID: <87ftv9ehla.fsf@codeaurora.org>
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Brian Norris <briannorris@chromium.org> writes:

> Comparing the existing TX_BITRATE parsing code (in
> mwifiex_parse_htinfo()) with the RX bitrate histograms in debugfs.c, it
> appears that the rxpd_rate and rxpd_htinfo fields have the same format.
> At least, they give reasonable results when I parse them this way.
>
> So this patch adds support for RX_BITRATE to our station info dump.
>
> Along the way, I add legacy bitrate parsing into the same function,
> using the debugfs code (mwifiex_histogram_read() and
> mwifiex_adjust_data_rate()) as reference.
>
> Additionally, to satisfy the requirements of
> NL80211_STA_INFO_RX_BITRATE, I skip logging the bitrate of multicast
> packets. This shouldn't add a lot of overhead to the RX path, as there
> are already several similar 802.3 header checks in this same codepath.
> We can also bias the branch behavior to favor unicast, as that's the
> common performance-sensitive case.
>
> I'd consider this support somewhat experimental, as I have zero
> documentation from Marvell. But the existing driver code gives me good
> reason to think this is correct.
>
> I've tested this on a few different 802.11{a,b,g,n,ac} networks, and the
> reported bitrates look good to me.
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> RFC: I'd appreciate it if someone from Marvell could double check my work
> here.

BTW, if we don't hear anything from Marvell I'm going to apply these
anyway.

-- 
Kalle Valo