From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933236Ab1EROkw (ORCPT ); Wed, 18 May 2011 10:40:52 -0400 Received: from home.keithp.com ([63.227.221.253]:39395 "EHLO keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752856Ab1EROkv (ORCPT ); Wed, 18 May 2011 10:40:51 -0400 From: Keith Packard To: Chris Wilson , Mihai Moldovan Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/i915/sdvo: Reorder i2c initialisation before ddc proxy In-Reply-To: References: <4DD2648C.6020309@ionic.de> <1305637430-16026-1-git-send-email-chris@chris-wilson.co.uk> User-Agent: Notmuch/0.5 (http://notmuchmail.org) Emacs/23.3.1 (i486-pc-linux-gnu) Date: Wed, 18 May 2011 07:40:42 -0700 Message-ID: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Transfer-Encoding: quoted-printable On Wed, 18 May 2011 09:04:11 +0100, Chris Wilson = wrote: > On Tue, 17 May 2011 18:22:52 -0700, Keith Packard wro= te: > > On Tue, 17 May 2011 14:03:50 +0100, Chris Wilson wrote: > > > The ddc proxy depends upon the underlying i2c bus being selected. Und= er > > > certain configurations, the i2c-adapter functionality is queried duri= ng > > > initialisation and so may trigger an OOPS during boot. Hence, we need= to > > > reorder the initialisation of the ddc proxy until after we hook up th= e i2c > > > adapter for the SDVO device. > >=20 > > I'd love more explanation here about how this code ever worked -- what > > are these 'certain configurations' of which you speak? >=20 > The condition under which it fails is when the i2c_add_adapter calls into > i2c_detect which will attempt to probe all valid addresses on the adapter > iff there is a pre-existing i2c_driver with the same class as the freshly > added i2c_adapter. Lovely. > So it appears to depend upon having compiled in (or loaded such a module > before i915.ko) an i2c-driver that likes to futz over the i2c_adapters > claiming DDC support. Thanks for your additional explanation, as I said, the patch looks sane on the face of it (always nice to initialize values before use). I've marked this as reviewed, added your additional explanation and merged it to drm-intel-next. Seems like it might like a cc to stable? =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iD8DBQFN09pqQp8BWwlsTdMRAlsXAJ9+kTMh6s/zd6IiZG4a2zhWDVm8zACcCuEm QBqaTWTHdT5NIbuTIscwckY= =sjqQ -----END PGP SIGNATURE----- --=-=-=--