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From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Felix Fietkau <nbd@nbd.name>
Cc: linux-wireless@vger.kernel.org,
	Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Subject: Re: [RFC] mt76: add 3dBm for reporting txpower also for 1x1
Date: Thu, 14 Mar 2019 14:50:12 +0100	[thread overview]
Message-ID: <20190314135011.GA15786@redhat.com> (raw)
In-Reply-To: <795dd253-53db-d837-4da6-6016a096cdc7@nbd.name>

On Wed, Mar 13, 2019 at 02:38:01PM +0100, Felix Fietkau wrote:
> On 2019-03-13 14:34, Stanislaw Gruszka wrote:
> > It's not clear for my why we should add 3dBm for 2x2 devices
> > and not for 1x1. 3dBm looks rater like minimal txpower and
> > hardware transmit at 3dBm + dev->txpower_cur / 2 .
> > 
> > With the change reported txpower value are closer to regulatory
> > values, but honestly I have no idea what should be reported.
> > 
> > Perhaps also some better comment should be added.
> > 
> > Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> The reason why we add 3dBm is because using two chains to transmit in
> the worst case (from regulatory point of view) doubles the transmit
> power (= +3dBm). There's no reason to do the same for 1x1.

Do we calculate and show correct txpower for mt76x0 then?

I have mt76x0u 50:3e:aa:a6:5d:32 and iwlmvm 1c:1b:b5:23:cf:58
devices on one laptop at the same location connected to AP.
RSSI values of both stations are quite similar:

Station 50:3e:aa:a6:5d:32 (on wlan0)
        inactive time:  4971 ms
        rx bytes:       11383
        rx packets:     97
        tx bytes:       2764
        tx packets:     17
        tx retries:     3
        tx failed:      1
        signal:         -55 [-65, -55] dBm
        signal avg:     -57 [-65, -57] dBm
        tx bitrate:     65.0 MBit/s MCS 6 short GI
        rx bitrate:     6.0 MBit/s
        authorized:     yes
        authenticated:  yes
        preamble:       long
        WMM/WME:        yes
        MFP:            no
        TDLS peer:      no
Station 1c:1b:b5:23:cf:58 (on wlan0)
        inactive time:  24261 ms
        rx bytes:       11320
        rx packets:     121
        tx bytes:       2274
        tx packets:     11
        tx retries:     0
        tx failed:      1
        signal:         -52 [-60, -52] dBm
        signal avg:     -54 [-59, -55] dBm
        tx bitrate:     6.5 MBit/s MCS 0
        rx bitrate:     6.0 MBit/s
        authorized:     yes
        authenticated:  yes
        preamble:       long
        WMM/WME:        yes
        MFP:            no
        TDLS peer:      no

On laptop txpower showed by iw for mt76x0u is 17 dBm , for iwlmvm
is 22 dBm (this is value from mac80211, iwlwifi does not implement
.get_txpower() callback). 

I do not consider this as big issue though, but can confuse some users.
Apparently confuses me.

Stanislaw

      parent reply	other threads:[~2019-03-14 13:50 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-13 13:34 [RFC] mt76: add 3dBm for reporting txpower also for 1x1 Stanislaw Gruszka
2019-03-13 13:38 ` Felix Fietkau
2019-03-13 14:11   ` Tom Psyborg
2019-03-13 14:21     ` Felix Fietkau
2019-03-14 13:50   ` Stanislaw Gruszka [this message]

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