From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754438AbbIBMKH (ORCPT ); Wed, 2 Sep 2015 08:10:07 -0400 Received: from mail-gw3-out.broadcom.com ([216.31.210.64]:5955 "EHLO mail-gw3-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752853AbbIBMKF (ORCPT ); Wed, 2 Sep 2015 08:10:05 -0400 X-IronPort-AV: E=Sophos;i="5.17,453,1437462000"; d="scan'208";a="73895473" Message-ID: <55E6E70F.80907@broadcom.com> Date: Wed, 2 Sep 2015 14:09:51 +0200 From: Arend van Spriel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: "Luis R. Rodriguez" , Ming Lei CC: Takashi Iwai , Linus Torvalds , Liam Girdwood , "Jie, Yang" , "Dmitry Torokhov" , "joonas.lahtinen@linux.intel.com" , Tom Gundersen , Al Viro , Greg Kroah-Hartman , Kay Sievers , David Woodhouse , "Luis Rodriguez" , lkml , yalin wang Subject: Re: Problems loading firmware using built-in drivers with kernels that use initramfs. References: <1440576394.2443.17.camel@loki> <20150829011130.GK8051@wotan.suse.de> <55E1724E.6040303@broadcom.com> <20150829183802.480b1425@tom-T450> <55E2BE0E.1070907@broadcom.com> <20150902011912.GY8051@wotan.suse.de> In-Reply-To: <20150902011912.GY8051@wotan.suse.de> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/02/2015 03:19 AM, Luis R. Rodriguez wrote: > On Mon, Aug 31, 2015 at 10:21:34PM +0800, Ming Lei wrote: >> On Sun, Aug 30, 2015 at 4:25 PM, Arend van Spriel wrote: >>> Does this mean a built-in driver can not get firmware from initramfs or >>> built in the kernel early. Seems a bit too aggressive. The problem stated in >>> this thread is when the firmware is not on initramfs but only on the rootfs. >> >> Yes, strictly speaking, user mode request can't be handled with defer probe >> during booting because we don't know how the user helper handles the >> request, > > FWIW I have a strategy in mind to help us compartamentalize the user mode > helper only to the dell-rbu driver, and as such phase out that code eventually > completely. Its part of the goals I have with the extensible firmware API I've > been proposing. > >> that said even checking if the firmware exists in current path doesn't >> make sense for user mode request. >> >> So the patch should have used defer proble for direct load only >> during booting. > > What exact guarantees would we be giving to callers if they follow up on probe > with -EDEFER_PROBE ? I'd much prefer to try to avoid such uses in init / probe > (note that unless you're using async probe since we batch both so it doesn't really > matter where you place your code) all together and then for the few remaining > stragglers understand the requirements and provide an interface that lets them > claim their requirements and try to meets them. > > A grammatical hunt for drivers who call fw API on init / probe can be > completed, although I know the hunt needs a bit more fine tuning it surely can > be completed. If we don't have many callers the compexity added for only a > few callers with rather loose criteria seems rather unnecessary, specially if > we can change the drivers and make these driver sthe exception rather than > a norm. > > Then as for drivers *needing* the fw at probe why not have a proper interface > that does guarantee they get the requirements they ask for first ? For instance > a new probe type specified by the driver could enable the core to wait for say > an event and then tirgger a probe, kind of how we ended up defining the async > probe type preference: > > static struct some_bus_driver some_driver = { > .probe = some_probe, > .id_table = some_id, > .driver = { > .name = DEVICE_NAME, > .pm = &some_pm_ops, > .probe_type = PROBE_PREFER_POST_FOO, > }, > }; > > Then we just don't try just hoping for completion but rather can do something > about the criteria passed. That sounds good to me and learning about the async probe type. We do a schedule work in our module_init to avoid the probe being done in init context. Guess we can change that using the async probe type :-p Regards, Arend