Return-path: Received: from mail-io0-f194.google.com ([209.85.223.194]:33740 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932084AbcAYWTm (ORCPT ); Mon, 25 Jan 2016 17:19:42 -0500 Received: by mail-io0-f194.google.com with SMTP id f81so14335315iof.0 for ; Mon, 25 Jan 2016 14:19:42 -0800 (PST) From: Nikolay Martynov To: linux-wireless@vger.kernel.org Cc: Nikolay Martynov , johannes.berg@intel.com, emmanuel.grumbach@intel.com, julian.calaby@gmail.com, ilw@linux.intel.com Subject: [PATCH v2] iwldvm: fix chain gain calibration when firmware return zero values Date: Mon, 25 Jan 2016 17:19:01 -0500 Message-Id: <1453760341-30008-1-git-send-email-mar.kolya@gmail.com> (sfid-20160125_231946_413409_76303A30) In-Reply-To: <1453527309-23881-1-git-send-email-mar.kolya@gmail.com> References: <1453527309-23881-1-git-send-email-mar.kolya@gmail.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: It looks like sometimes firmware returns zero for chain noise and signal during calibration period. This seems to be a known problem and current implementation accounts for this by ignoring invalid data when all chains return zero signal and noise. The problem is that sometimes firmware returns zero for only one chain for some (not all) beacons used for calibration. This leads to perfectly valid chains be disabled and may cause invalid gain settings. For example this is calibration data taken on laptop with Intel 6300 card with all three antennas attached: active_chains: 3 chain_noise_a: 312 chain_noise_b: 297 chain_noise_c: 0 chain_signal_a: 549 chain_signal_b: 513 chain_signal_c: 0 beacon_count: 16 disconn_array: 0 0 1 delta_gain_code: 4 0 0 radio_write: 1 state: 3 This patch changes statistics gathering to make sure that zero noise results are ignored for valid rx chains. The rationale being that even if anntenna is not connected we should be able to see non zero noise if rx chain is present. This patch fixes the problem of disabling working chains on hardware I have (6300 and 5300). With three connected antennas statistics in chain_noise looks like this (6300): active_chains: 7 chain_noise_a: 321 chain_noise_b: 243 chain_noise_c: 311 chain_signal_a: 559 chain_signal_b: 452 chain_signal_c: 512 beacon_count: 16 disconn_array: 0 0 0 delta_gain_code: 4 3 0 radio_write: 1 state: 3 It also works fine in case one 3-chain hardware has only two antennas attached (tested in 5300): active_chains: 3 chain_noise_a: 238 chain_noise_b: 234 chain_noise_c: 219 chain_signal_a: 533 chain_signal_b: 514 chain_signal_c: 206 beacon_count: 16 disconn_array: 0 0 1 delta_gain_code: 4 0 0 radio_write: 1 state: 3 Signed-off-by: Nikolay Martynov --- drivers/net/wireless/iwlwifi/dvm/calib.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/net/wireless/iwlwifi/dvm/calib.c b/drivers/net/wireless/iwlwifi/dvm/calib.c index 20e6aa9..cdaa88d 100644 --- a/drivers/net/wireless/iwlwifi/dvm/calib.c +++ b/drivers/net/wireless/iwlwifi/dvm/calib.c @@ -1026,6 +1026,18 @@ void iwl_chain_noise_calibration(struct iwl_priv *priv) spin_unlock_bh(&priv->statistics.lock); + /* Sometimes firmware returns zero for chain noise and signal + * even if chain is present and antenna is connected. This + * often results in perfectly valid chains being disabled. + * Ignore statistics if it contains zero noise for valid rx + * chain: even with antenna disconnected we should hear some noise. + */ + if ((priv->nvm_data->valid_rx_ant & ANT_A && chain_noise_a == 0) || + (priv->nvm_data->valid_rx_ant & ANT_B && chain_noise_b == 0) || + (priv->nvm_data->valid_rx_ant & ANT_C && chain_noise_c == 0)) { + return; + } + data->beacon_count++; data->chain_noise_a = (chain_noise_a + data->chain_noise_a); -- 2.7.0