Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755010Ab2HIHgs (ORCPT ); Thu, 9 Aug 2012 03:36:48 -0400 Received: from moutng.kundenserver.de ([212.227.126.186]:56563 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751705Ab2HIHgq (ORCPT ); Thu, 9 Aug 2012 03:36:46 -0400 Date: Thu, 9 Aug 2012 09:36:42 +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: <20120809073642.GA24695@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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="C7zPtVaVf+AK4Oqc" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Provags-ID: V02:K0:GEHzmL8Q6pZz4eu5Wpz80ICKLu+PO632+pSxD1L6oMw sYnp9Js4gQm+W6Pl3+HIeYyAojulfYZxjKZj83LF4sFhcGNPFG yY80/k6kDtuLFeihlxdJcmwG3/qbSvS2gNKwobQ7O8fTL53KgE KQpfDErMXR1ldf6mPm0VsmQc17/v4Rb5wb8tlVww8XslRqy0i5 S10SfQWbGA9AdXULOxSg2x7iwMqZjF+xWt6XpwJBvdZaLGiFgX 0LPOFgtNlLOYsNAxQXXa7Ce3sfw1tR78p5ZZga7e9tcNEbmuDH 85AvjowzyCwcE2sJbHr7XMyDLO1y0xbpG9QdDX3j1GnFWGj1uF nsSMOzAz7QD06KE8/1RvLXVvw/wmbw2EsWORRR6NWM4EKjVhH7 AhDUiuGtZHIy3vk9hKvkghi+APLUQ/fWNQ= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3172 Lines: 81 --C7zPtVaVf+AK4Oqc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 sta= ll > > > > when firmware is loaded during the module_init() call. The snd-hda-= intel > > > > module requests firmware if the patch=3D parameter is used to load = a patch > > > > file. This patch works around the problem by deferring the probe in= such > > > > cases, which will cause the module to load successfully and the dri= ver > > > > 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-infrastructur= e/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. 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. A proper fix would require a larger rewrite because it would entail using the asynchronous firmware load operations. That in turn would require the initialization to be split into several stages. Thierry --C7zPtVaVf+AK4Oqc Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iQIcBAEBAgAGBQJQI2iKAAoJEN0jrNd/PrOh7YMP/iGuXFqC9foVDzFA3hij87hZ 6x/TYMtVTWPU3A2Gwc9+7ryj1JJCEvZFwxf4wmXN1+CV9FLBfm6El/I8j2RgJ5QE LqHvfLppamd0UkI83w53qHpIB6YFZTv8Y/8fOz07GV6r9KK6xclruNqLVilQnhnJ gLYTbcm4thjRswSnY3Fw2KVDZnbRwyVS18Xxp1jBjwaqdGoF343WJQjj5EHaUp3Q Bx+TILcrsCOzotfg+SpX6mTRXAr5/r4UhGxuxlhJKUL3x5JO7Z+9mbeo3PsfT0bk XIIlYwIVqRVlSgKSjbn8Om+f57FmTcg1zEypnaQLMT9jNB+ouk0BUQDztZn3QKND Ezwc7jiFMr6ViOwh2x+SCVwsMgXQuLLOaZOPg+F1TnC3DO9wMGS0Nb4eHem4tvT1 AZ43Z4RW3murFnWTOh6XWwSwOasD+DAK64dJxfkjkfw6S0tQz63KoG2kmT86hq+O p3mdgiCbRVo2PkyT9JdhMmBQpD4Rt3NXZ+4kgBLa+X8IP2fKu3rWsRjyIJ4FlGb1 KOijWqIFpzPNnevHnndqnk317FwulOHVgIDG5rF1iibqOT2zZQwlzHlFcFqLtcC+ fp2iomhBwl61n1nf1nH54Y9wuBNCoqHznIAVq4iAkpx64Eml9wy9ssT6UDoHNKbv Zmk708UiY8j+XEhJ/UhD =o5gv -----END PGP SIGNATURE----- --C7zPtVaVf+AK4Oqc-- -- 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/