Return-path: Received: from mms2.broadcom.com ([216.31.210.18]:3211 "EHLO mms2.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751568Ab2BTKCD (ORCPT ); Mon, 20 Feb 2012 05:02:03 -0500 Message-ID: <4F421A0E.8030805@broadcom.com> (sfid-20120220_110255_440931_235AF71A) Date: Mon, 20 Feb 2012 11:01:50 +0100 From: "Arend van Spriel" MIME-Version: 1.0 To: "Larry Finger" cc: LKML , driverdevel , wireless , "linux-hotplug@vger.kernel.org" , "Kay Sievers" Subject: Re: will these methods work with firmware loading? References: <4F414230.5040506@lwfinger.net> In-Reply-To: <4F414230.5040506@lwfinger.net> Content-Type: text/plain; charset=iso-8859-1; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 02/19/2012 07:40 PM, Larry Finger wrote: > I sent a previous messages to most of these lists, but got no answer, thus a > second try. > > When a driver loads firmware synchronously in the module_init() path using > request_firmware(), then there is trouble with timeouts when booting. > > I know that changing the request_firmware() call to request_firmware_nowait() > solves the problem; however, that gives some trouble for driver b43legacy as it > loads 3 or 4 firmware files depending on the hardware version. When I launch the > 3 or 4 nowait requests, I get an error because the system is trying to start > several tasks with the same name. Yep, the nowait api just kicks off a kernel thread for the firmware request. > Would it be OK to load the first file with the nowait version, and issue a > request_firmware() for the others from the callback routine? I think that would > not cause any problems, but I would like to get confirmation from an expert. No expert, but that is what I did although the chaining of firmware requests does not feel great. Especially for handling error flows. Johannes Berg and Kay Sievers mentioned need to unbind/rebind the driver upon failed firmware load, but I don't like the idea of building a timer-controlled retry mechanism. > Similarly, if I were to create a work queue, init and schedule it from > module_init(), and then use synchronous loads to get the firmware from the work > queue callback, would that get around the boot problem? I know it works as I > have trial patches; however, my version of udev is not one affected. This method > is very easy to implement, but again I would like confirmation from an expert. What boot problem are you referring to? The blocking modprobe? For that problem I would say yes. Also here the problem of handling error flows exist. If the driver is kicked of during boot with a initramfs missing the firmware, should we retry until the real root is mounted? Gr. AvS