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From: Felix Fietkau <nbd@nbd.name>
To: Jean Pierre TOSONI <jp.tosoni@acksys.fr>,
	Kalle Valo <kvalo@codeaurora.org>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"ath9k-devel@qca.qualcomm.com" <ath9k-devel@qca.qualcomm.com>
Subject: Re: [PATCH v2] ath9k: mark RSSI as invalid if frame received during channel setup
Date: Thu, 15 Feb 2018 15:45:48 +0100	[thread overview]
Message-ID: <ab149f51-bd2e-871c-b429-2772dfa1b48c@nbd.name> (raw)
In-Reply-To: <AM4PR0101MB230538DEEFCFFC0E0F4437A2E4F50@AM4PR0101MB2305.eurprd01.prod.exchangelabs.com>

On 2018-02-14 17:26, Jean Pierre TOSONI wrote:
> ath9k returns a wrong RSSI value for frames received in a 30ms time
> window after a channel change. The correct value is typically 10dB
> below the returned value.
> 
> This was found with a Atheros AR9300 Rev:3 chip (WLE350NX / JWX6083
> cards), during offchannel scans.
> 
> Mark the signal value as invalid in this case.
> 
> Signed-off-by: Jean Pierre TOSONI <jp.tosoni@acksys.fr>
It seems that this will potentially cause a lot of scan results with
RSSI information missing, which I think may be worse than a 10 db
fluctuation.
Actually, it could also be that the hardware is reporting accurate RSSI
values (they're reported as SNR relative to the noise floor) and this is
just a blip caused by the fact that the hw is updating its internal
noise floor value based on running measurements.

Does the same fluctuation also happen if you set update = false for
calls to ath9k_hw_start_nfcal?

- Felix

  parent reply	other threads:[~2018-02-15 14:45 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-14 16:26 [PATCH v2] ath9k: mark RSSI as invalid if frame received during channel setup Jean Pierre TOSONI
2018-02-14 18:16 ` Steve deRosier
2018-02-15  8:48   ` Jean Pierre TOSONI
2018-02-14 21:30 ` James Cameron
2018-02-15  5:51   ` Kalle Valo
2018-02-15  7:21     ` James Cameron
2018-02-15  8:52       ` Jean Pierre TOSONI
2018-02-15 11:57         ` James Cameron
2018-02-15 14:45 ` Felix Fietkau [this message]
2018-02-15 16:29   ` Jean Pierre TOSONI

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