Return-path: Received: from bues.ch ([80.190.117.144]:39942 "EHLO bues.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998Ab3CWKfi (ORCPT ); Sat, 23 Mar 2013 06:35:38 -0400 Date: Sat, 23 Mar 2013 11:35:17 +0100 From: Michael =?UTF-8?B?QsO8c2No?= To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: Larry Finger , linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org, isedev@gmail.com Subject: Re: [PATCH] b43: A fix for DMA transmission sequence errors Message-ID: <20130323113517.01906b0b@milhouse> (sfid-20130323_113542_805052_A881409C) In-Reply-To: References: <514a07c7.ZQz6MhmMaq58WJlA%Larry.Finger@lwfinger.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/uKzXFLyv0QY2hOYTnefKETt"; protocol="application/pgp-signature" Sender: linux-wireless-owner@vger.kernel.org List-ID: --Sig_/uKzXFLyv0QY2hOYTnefKETt Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Sat, 23 Mar 2013 00:27:30 +0100 Rafa=C5=82 Mi=C5=82ecki wrote: > Today I've plugged my 14e4:4315 and (unfortunately?) it's working > pretty well. I hoped to reproduce some problems but failed to do so. I > was transmitting for an hour with average speed 11MiB/s and didn't > notice any DMA issues. >=20 > I was using iperf with interval of 60 seconds and only 3 results > showed some problems (8.5MiB/s, 2.5MiB/s, 4.5MiB/s). No disconnections > however and no DMA errors. I just got "Group rekeying completed..." in > wpa_supplicant. >=20 > So as I can't reproduce this, I can't find any other fix for this > issue, and there's no reason to stop this workaround. I'll just apply > it and test over weekend to check for any regressions, but they are > highly unlikely. I don't really believe in this being a firmware bug. Some b43 DMA engines (all?) have some alignment and page-boundary-crossing constraints. I would rather guess that on some kernels with some options turned on, alignment and/or boundary constraints are violated every now and then. (and thus the packet never reaches the firmware). I don't remember the details, though. Too long since I worked on that. But a few sanity checks could probably be added to the code to check this hypothesis. Does the failing kernel/machine have any special things w.r.t. memory? Like iommu, hugepages, whetever... --=20 Michael --Sig_/uKzXFLyv0QY2hOYTnefKETt Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJRTYVlAAoJEPUyvh2QjYsO+xQP/3yIpevmrHAhTJ0fy2z3wkkm KzYmOoDhY1uoCeQdtaqSJyiF0zRJ9HmGrzapptRVpv2GiMoUs+B0PnP4mhqCVbI3 hXL6hvLqNb3s2YadhQPG3NWRasZCElA1STVVRhWciOFXriIDohMijcW7lKa+0XWR bWT1txeHhu9cUWnSB6aETWcx1EduAwGoDy1kVRyR/6gbe64quxHNviX2wZ88eKBu WMWoyJMmEO1GZgfIEKK9stHZRYt9pjFHClzd2+uWxzjE557/wniwLH659CAeMULl LYFsCo19cKOjgTQ19iF282OR9dkHKBjwLYXIUPIU48SjjGOqtjSFYPvM7Y1bDC8j XcWY0b7rP6qzr8IMGCghoI6Nw9CeTeUdgWOd3dxazklDzreIkFYeLf2nJEDNvfmO A7LLGeOPfQjlCYO9Rh0FL2vE6125lcsW4XzeRRqG++iqFz3DIbEPRjYD7D1GDGX5 ps172GVKcikbsFBvdlWIl7LfBiNEpD3yGJDlRX1ITdYLtBuEB65LmvTGoLeSGiq1 Nz4AB2I3mtIZgyPHmRBfs+Xx0c0xeMpGdQGRzm23NeUrPUp7oird8zKFAAwHVbyn zVbbid6kPOU6UC1YYKBrhvxp9nfgkzsyNW0oGSr4x7eGxbZ2FnrRUxSp0Hdix9mv M3qOPpWf9tUEoQDr22Xk =x7a4 -----END PGP SIGNATURE----- --Sig_/uKzXFLyv0QY2hOYTnefKETt--