Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756190Ab2HIIHb (ORCPT ); Thu, 9 Aug 2012 04:07:31 -0400 Received: from moutng.kundenserver.de ([212.227.17.10]:60116 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755366Ab2HIIHS (ORCPT ); Thu, 9 Aug 2012 04:07:18 -0400 Date: Thu, 9 Aug 2012 10:07:13 +0200 From: Thierry Reding To: Takashi Iwai Cc: Jaroslav Kysela , David Henningsson , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ALSA: hda - Defer probe when loading patch firmware Message-ID: <20120809080713.GC24808@avionic-0098.mockup.avionic-design.de> References: <1344494723-6827-1-git-send-email-thierry.reding@avionic-design.de> <20120809070813.GA6979@avionic-0098.mockup.avionic-design.de> <20120809073642.GA24695@avionic-0098.mockup.avionic-design.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ALfTUftag+2gvp1h" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Provags-ID: V02:K0:WChr0QcPYh4SUmbNZmk/Ob4ugxTtX2kNiRf6+x3VZ5D QTHG3JSK5nuWFT07sEo0hlG6EQHgYSO4WEAkdmuCY3ej1ZQhig sQ+trf8ZBqZZLnUA/SF83HOlAmXln1t5T0XnMMsDE44jn7r5us IeJsTJVG1+r8efGJoDzorpQfLroej4a/e6LlT8+LyVe6YghttJ OnrNg6WZac+kAIvR/MvwUwzHmXTi+qWapFdyhcA+KpZL4xZ2aa wIqQUyj58eka9Yn82JjrzZeq0IBPaADtxwdZYOsEg3Yub00pqh CvDThpODmKwLWIPUIErKv8c0xblNgshf5x4vQL+MC5/ShoOhev FH+nFvwgfIhj+poutKMSrZO1sobE4M3ky7w3x+t4F/Y7BDDwFQ xt+f/+9ZBHPfoO/mwUHF5Kkk3lgoqPDGcmZfrPJqhuZruWQ3k9 2aLvF Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4136 Lines: 104 --ALfTUftag+2gvp1h Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 09, 2012 at 09:42:48AM +0200, Takashi Iwai wrote: > At Thu, 9 Aug 2012 09:36:42 +0200, > Thierry Reding wrote: > >=20 > > On Thu, Aug 09, 2012 at 09:31:30AM +0200, Takashi Iwai wrote: > > > At Thu, 9 Aug 2012 09:08:13 +0200, > > > Thierry Reding wrote: > > > >=20 > > > > On Thu, Aug 09, 2012 at 08:57:13AM +0200, Takashi Iwai wrote: > > > > > At Thu, 9 Aug 2012 08:45:23 +0200, > > > > > Thierry Reding wrote: > > > > > >=20 > > > > > > Recent changes to the firmware loading helpers cause drivers to= stall > > > > > > when firmware is loaded during the module_init() call. The snd-= hda-intel > > > > > > module requests firmware if the patch=3D parameter is used to l= oad a patch > > > > > > file. This patch works around the problem by deferring the prob= e in such > > > > > > cases, which will cause the module to load successfully and the= driver > > > > > > binding to the device outside the module_init() call. > > > > >=20 > > > > > Is the "recent" change meant 3.6 kernel, or in linux-next? > > > > >=20 > > > > > In anyway, I don't understand why such a change was allowed. Most > > > > > drivers do call request_firmware() at the device probing time. > > > > > If this really has to be resolved in the driver side, it must be = a bug > > > > > in the firmware loader core code. > > > >=20 > > > > A good explanation of the problem and subsequent discussion can be = found > > > > here: > > > >=20 > > > > http://article.gmane.org/gmane.linux.drivers.video-input-infrastru= cture/49975 > > >=20 > > > Yeah, but it doesn't justify this ugly module option. > > > It's a simple bug. Papering over it with this option doesn't fix > > > anything. > >=20 > > It's not an option, all it does is defer probing if and only if the > > patch parameter was specified to make sure the firmware load won't > > stall. I realize that this may not be an optimal solution, but at least > > it fixes the problem with no fallout. >=20 > Ah sorry, I misread the patch. >=20 > Then it shouldn't be checked at that point. Since 3.5 kernel, the > probing code was already split for vga_switcheroo support. Yes, I saw that. But unless you actually use vga_switcheroo, the second stage, azx_probe_continue(), will still be called from azx_probe() and therefore ultimately from module_init(). Before coming up with this patch I actually did play around a bit with using the asynchronous firmware load functions but it turned out to be rather difficult to do so I opted for the easy way. The biggest problem I faced was that since patch loading needs to be done very early on, a lot of the initialization would need to be done after .probe() and many things could still fail, so cleaning up after errors would become increasingly difficult. > The point you added is the second stage. I don't understand this sentence. Thierry --ALfTUftag+2gvp1h Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJQI2+xAAoJEN0jrNd/PrOhG0wQAK7trGSUmaPTd5R5TcSi7Vf0 khWVDAFYenheo3ZUqb4mdPZMA8VoaL0o/DZ+tRi7rj8lxYGR3XO53WmXp5RMWx0b +UHr33K1sJvtJWypfuejt2qqxhWlU9dqEGdcV2ZAhM9ImEkWftEAjG9BK8ooJi0Q GCGe4ijYFkybaSmI9QJ6ktVVt99f+cMy9j9+lJN3PuixcVpt6HEV1msgKAP4gg78 x6vduw4/D9r68kQxi3VKQY9eMRr2B+x3m/7ZDddT9MmHG1DMjYr0Uv0VGQjAYlJ9 xP+ynkzDyd6LeirQ1lTbCRjuSK7Wqfd6SCqWff2mFDOfS262rbO4ZpLCxyXlYGqn ZE2bzyyFHQApWkpBJmcw5lhZt1/4GsbGt9WnW4BLot2pmOk61eHv+It2AGLln8iq SlFXoVK2NrjDiFmgU9atzjz9iAzM1knjCq2RH+uqVyETukgPPrl8i3VgYMRc4DLt ntPPgPl3W7Mcd1VcvaZDhppnrlKd8Pb1ObKHNlsGK7Qjwk0WeeWlE+ODqf9kX4xT +bvsffUpX72vhvJeQ36OWTER4YFH3xOzbUcy4wItfJ6/sSaFNxD0f9QfOUdZdBW/ qD5OkQAdZcS8xqqrg/qP/51ULaPn4FB8vTmpAYtCkFt3nxssnlDWyTfpNykxHZzF gMpVtwzBPI6Bz8SBjObe =T8J3 -----END PGP SIGNATURE----- --ALfTUftag+2gvp1h-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/