Return-path: Received: from swan.media.mit.edu ([18.85.44.157]:44329 "EHLO swan.laptop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752132AbeBFEeh (ORCPT ); Mon, 5 Feb 2018 23:34:37 -0500 Date: Tue, 6 Feb 2018 15:34:30 +1100 From: James Cameron To: Larry Finger Cc: kvalo@codeaurora.org, linux-wireless@vger.kernel.org, Stable Subject: Re: [PATCH] rtlwifi: rtl8821ae: Fix connection lost problem correctly Message-ID: <20180206043430.GF31854@us.netrek.org> (sfid-20180206_053441_215412_B0EACE51) References: <20180205183811.19526-1-Larry.Finger@lwfinger.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180205183811.19526-1-Larry.Finger@lwfinger.net> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, Feb 05, 2018 at 12:38:11PM -0600, Larry Finger wrote: > There has been a coding error in rtl8821ae since it was first introduced, > namely that an 8-bit register was read using a 16-bit read in > _rtl8821ae_dbi_read(). This error was fixed with commit 40b368af4b75 > ("rtlwifi: Fix alignment issues"); however, this change led to > instability in the connection. To restore stability, this change > was reverted in commit b8b8b16352cd ("rtlwifi: rtl8821ae: Fix connection > lost problem"). > > Unfortunately, the unaligned access causes machine checks in ARM > architecture, and we were finally forced to find the actual cause of the > problem on x86 platforms. Following a suggestion from Pkshih > , it was found that increasing the ASPM L1 > latency from 0 to 7 fixed the instability. This parameter was varied to > see if a smaller value would work; however, it appears that 7 is the > safest value. A new symbol is defined for this quantity, thus it can be > easily changed if necessary. > > Fixes: b8b8b16352cd ("rtlwifi: rtl8821ae: Fix connection lost problem") > Cc: Stable # 4.14+ > Fix-suggested-by: Pkshih > Signed-off-by: Larry Finger Tested-by: James Cameron # x86_64 OLPC NL3 Thanks Larry & Pkshih, this does work as well as it did before. -- James Cameron http://quozl.netrek.org/