Return-path: Received: from store.laptop.org ([18.85.44.157]:57569 "EHLO swan.laptop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751003AbdILWT5 (ORCPT ); Tue, 12 Sep 2017 18:19:57 -0400 Date: Wed, 13 Sep 2017 08:09:16 +1000 From: James Cameron To: linux-wireless@vger.kernel.org Cc: Ping-Ke Shih , Larry Finger , Kalle Valo Subject: rtl8821ae keep alive not set, connection lost Message-ID: <20170912220916.GB32211@us.netrek.org> (sfid-20170913_002001_084723_13FE9F6F) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: Summary: 40b368af4b75 ("rtlwifi: Fix alignment issues") breaks rtl8821ae keep alive, causing "Connection to AP lost" and deauth, but why? Wireless connection is lost after a few seconds or minutes, on every OLPC NL3 laptop with rtl8821ae, with any stable kernel after 4.10.1, and any kernel with 40b368af4b75. dmesg contains wlp2s0: Connection to AP 2c:b0:5d:a6:86:eb lost iw event shows wlp2s0: del station 2c:b0:5d:a6:86:eb wlp2s0 (phy #0): deauth 74:c6:3b:09:b5:0d -> 2c:b0:5d:a6:86:eb reason 4: Disassociated due to inactivity wlp2s0 (phy #0): disconnected (local request) Workaround is to bounce the link, then reconnect; ip link set wlp2s0 down ip link set wlp2s0 up iw dev wlp2s0 connect qz A nearby monitor host captures a deauthentication packet sent by the device. Bisection showed cause is 40b368af4b75 ("rtlwifi: Fix alignment issues") which changes the width of DBI register read. On the face of it, 40b368af4b75 looks correct, especially compared against same function in rtl8723be. I've no idea why reverting fixes the problem. I'm hoping someone here might speculate and suggest ways to test. As keep alive is set through this path, my guess is that keep alive is not being set in the device. Or perhaps reading 16-bits perturbs another register. Is there a way to test? http://dev.laptop.org/~quozl/z/1drtGD.txt dmesg of 4.13 http://dev.laptop.org/~quozl/z/1drt7c.txt dmesg with 4.13 and revert of 40b368af4b75 -- James Cameron http://quozl.netrek.org/