Return-path: Received: from smtp.nokia.com ([147.243.1.48]:44073 "EHLO mgw-sa02.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751210Ab1AQLca (ORCPT ); Mon, 17 Jan 2011 06:32:30 -0500 From: juuso.oikarinen@nokia.com To: coelho@ti.com Cc: linux-wireless@vger.kernel.org Subject: [PATCH] wl12xx: Increase scan channel dwell time for passive scans Date: Mon, 17 Jan 2011 13:32:23 +0200 Message-Id: <1295263943-32110-1-git-send-email-juuso.oikarinen@nokia.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: From: Juuso Oikarinen The passive scan channel dwell time currently used is 30ms-60ms. A typical beacon interval for AP's is 100ms. This leads to a ~30% worst-case probability of finding an AP via passive scanning. For 5GHz bands for DFS frequencies passive scanning is the only scanning option. Hence for these, the probability of finding an AP is very low. To fix this, increase the passive channel scan dwell times (also the early leave value, as 5GHz channels are still typically very silent.) Use a value of 100ms, because that covers most typical AP configurations. Based on testing the probability of finding an AP (102.4ms beacon interval) on a single scan round are as follows (based on 100 iterations): dwell min/max (ms) | probability ---------------------+------------ 30/60 | 35% 60/60 | 56% 80/80 | 77% 100/100 | 100% Total scan times now and after the change: Region | Before (s) | After (s) -------+------------+---------- 00 | 0.77 | 1.48 FI | 0.95 | 2.01 US | 0.91 | 1.76 Signed-off-by: Juuso Oikarinen --- drivers/net/wireless/wl12xx/conf.h | 16 ++++++++-------- drivers/net/wireless/wl12xx/main.c | 4 ++-- 2 files changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/net/wireless/wl12xx/conf.h b/drivers/net/wireless/wl12xx/conf.h index f5c048c..21b72a5 100644 --- a/drivers/net/wireless/wl12xx/conf.h +++ b/drivers/net/wireless/wl12xx/conf.h @@ -1084,30 +1084,30 @@ struct conf_scan_settings { /* * The minimum time to wait on each channel for active scans * - * Range: 0 - 65536 tu + * Range: u32 tu/1000 */ - u16 min_dwell_time_active; + u32 min_dwell_time_active; /* * The maximum time to wait on each channel for active scans * - * Range: 0 - 65536 tu + * Range: u32 tu/1000 */ - u16 max_dwell_time_active; + u32 max_dwell_time_active; /* * The maximum time to wait on each channel for passive scans * - * Range: 0 - 65536 tu + * Range: u32 tu/1000 */ - u16 min_dwell_time_passive; + u32 min_dwell_time_passive; /* * The maximum time to wait on each channel for passive scans * - * Range: 0 - 65536 tu + * Range: u32 tu/1000 */ - u16 max_dwell_time_passive; + u32 max_dwell_time_passive; /* * Number of probe requests to transmit on each active scan channel diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c index 863e660..c1814f2 100644 --- a/drivers/net/wireless/wl12xx/main.c +++ b/drivers/net/wireless/wl12xx/main.c @@ -279,8 +279,8 @@ static struct conf_drv_settings default_conf = { .scan = { .min_dwell_time_active = 7500, .max_dwell_time_active = 30000, - .min_dwell_time_passive = 30000, - .max_dwell_time_passive = 60000, + .min_dwell_time_passive = 100000, + .max_dwell_time_passive = 100000, .num_probe_reqs = 2, }, .rf = { -- 1.7.1