Return-path: Received: from civicrm.laptop.org ([18.85.44.157]:55267 "EHLO swan.laptop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754800AbeBOHVd (ORCPT ); Thu, 15 Feb 2018 02:21:33 -0500 Date: Thu, 15 Feb 2018 18:21:18 +1100 From: James Cameron To: Kalle Valo Cc: Jean Pierre TOSONI , "linux-wireless@vger.kernel.org" , "ath9k-devel@qca.qualcomm.com" Subject: Re: [PATCH v2] ath9k: mark RSSI as invalid if frame received during channel setup Message-ID: <20180215072118.GG17837@us.netrek.org> (sfid-20180215_082136_871250_1789D99A) References: <20180214213025.GB17837@us.netrek.org> <87mv0a6brz.fsf@kamboji.qca.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <87mv0a6brz.fsf@kamboji.qca.qualcomm.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Feb 15, 2018 at 07:51:28AM +0200, Kalle Valo wrote: > James Cameron writes: > > > On Wed, Feb 14, 2018 at 04:26:42PM +0000, 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. > > > > How was your correct value determined? > > > >> 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. > > > > Why not adjust by 10dB? > > > > Speculating: in a typical card, RSSI is calculated by firmware from > > readings of ADCs attached to the receiver. Firmware may average > > several readings. Firmware may apply other offsets or calibrations, > > based on frequency and temperature. This sounds like a firmware > > problem. > > ath9k does not have firmware, only ath9k_htc has it. Heh. s/firmware/silicon implementation/g -- James Cameron http://quozl.netrek.org/