Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752008AbdCCKRN (ORCPT ); Fri, 3 Mar 2017 05:17:13 -0500 Received: from www.zeus03.de ([194.117.254.33]:50820 "EHLO mail.zeus03.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751612AbdCCKRH (ORCPT ); Fri, 3 Mar 2017 05:17:07 -0500 Date: Fri, 3 Mar 2017 11:17:02 +0100 From: Wolfram Sang To: Paul Menzel Cc: Christian Fetzer , Jean Delvare , linux-i2c@vger.kernel.org, linux-watchdog@vger.kernel.org, 853122@bugs.debian.org, Wim Van Sebroeck , Guenter Roeck , Tim Small , Nehal Shah , Mika Westerberg , Andy Shevchenko , Thomas Brandon , Eddi De Pieri , linux-kernel@vger.kernel.org Subject: Re: [Regression] Changes to i2c-piix4.c initialisation prevent loading of sp5100_tco watchdog driver on AMD SB800 chipset Message-ID: <20170303101702.GA1669@katana> References: <1485728348.3220.10.camel@googlemail.com> <1488530782.2457.41.camel@users.sourceforge.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="VbJkn9YxBvnuCH5J" Content-Disposition: inline In-Reply-To: <1488530782.2457.41.camel@users.sourceforge.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2710 Lines: 69 --VbJkn9YxBvnuCH5J Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > Unfortunately, commit 2fee61d22e (i2c: piix4: Add support for > multiplexed main adapter in SB800) [1] caused a regression. Tim > reported that to the Linux Kernel Bugtracker as bug #170741 last > September [2], but it looks like the affected subsystems don=E2=80=99t us= e it. Jean Delvare pointed out this issue amongst others[1] last year already. Let me quote: =3D=3D=3D 5* The I/O ports used for SMBus configuration and port switching are also needed by a watchdog driver, sp5100_tco. Both drivers request the region, so the first one wins, and the other driver can't be loaded. sp5100_tco was there first, so the changes done to the i2c-piix4 driver recently will cause a regression for some users by preventing them =66rom using the sp5100_tco and i2c-piix4 drivers at the same time. In the long run I guess we will need a helper module to handle this shared resource. Unless IORESOURCE_MUXED can be used for that. Either way, that's more work than I can put into this before kernel v4.5 is released. For the time being, I think we should simply make it non-fatal if the I/O ports can't be requested, and continue without multiplexing (as before.) =3D=3D=3D Seems nobody had the resources, so far. I don't have the HW and not much experience with non-embedded platforms. I wonder, though, if we really need to convert the drivers to MFD ones, or if we could use the simpler MFD_SYSCON mechanism which helps in exactly such cases for embedded platforms. But I am really lacking details here and am afraid this is probably all the input I can give currently. Regards, Wolfram [1] http://www.spinics.net/lists/linux-i2c/msg23437.html --VbJkn9YxBvnuCH5J Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJYuUKeAAoJEBQN5MwUoCm2Or4P/20b2b3/GqmB3oR96CELtrGG 6HLRlYxaF3T/TBDcjevDyD+q20FBWynWl32t+4ZDAwdgtsWj9MyT0G+OzgxwpNCS /OUWHyYJX1q9wfdlKnRDMA2+qvZaPhujuPLC+/Ny3WiuHA5YhFBY9PAJcUwTJUgP eAw/zP4oXU31wiLszgxVjIoXEMh7IhvJ+5XvI3NIFjwH8OuUsgWDikvEc43v4d7/ DR+Yy7DPVOXnjlG0oMOAkUJbXzww+rKBbRhay7BfS2oQGt/4tp3LpBdJYN1o2jN9 Ba+kt/Kai+yYXQ3IB9knj+xuLgPoS1a0FnDVSdyGok/KXvjPuvycAxOsRvevNgGT lnk9pwzURd0fhWsuT7haC07iPl+NUh2dxbuAkK7NwVI7l4TB/7dymaRI2AORjS9J CH/Fx1nMzUVsvfHcecpgdfWzLH8rs6f7ZHbDpP0AMLsCsJZXmQA934STHBBxhdhr 8a1ep+GdsPF83g8KvNRG4q00rBTAHBDfZTrBLp/+xYiSmqrCtjYrsU7JlyK2Tgon nIWrp2XeF7gozhKKtL2N9PfLl3cmaXCqwTgzG9iyi4Bks6OruB0RQGDmULBPDN7I DdkIc0WN752T3WiZdkbqu7Q9oBQNV35SHOfSaz4g257TRLYM46vG8w06Y0+HzOfz cnBfLqPA8OYVA1Mvhh16 =madV -----END PGP SIGNATURE----- --VbJkn9YxBvnuCH5J--