From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 114D078D for ; Tue, 2 Aug 2016 22:54:56 +0000 (UTC) Received: from cloudserver094114.home.net.pl (cloudserver094114.home.net.pl [79.96.170.134]) by smtp1.linuxfoundation.org (Postfix) with SMTP id EDA38218 for ; Tue, 2 Aug 2016 22:54:54 +0000 (UTC) From: "Rafael J. Wysocki" To: Linus Walleij Date: Wed, 03 Aug 2016 01:00:06 +0200 Message-ID: <4207317.8s4bUitgDu@vostro.rjw.lan> In-Reply-To: References: <20160726223054.GA30993@dtor-ws> <5799DB1B.5010307@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Cc: "ksummit-discuss@lists.linuxfoundation.org" , Marek Szyprowski Subject: Re: [Ksummit-discuss] Self nomination List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tuesday, August 02, 2016 10:09:17 AM Linus Walleij wrote: > On Thu, Jul 28, 2016 at 12:14 PM, Marc Zyngier wrote: > > On 26/07/16 23:30, Dmitry Torokhov wrote: > > >> - I would like to sync up with people and discuss [lack of] progress > >> on topic of device probe ordering (including handling of deferred > >> probes, asynchronous probes, etc). > > > > I'm extremely interested in discussing this. > > I've also tried to pitch in on it in the past but I just feel stupid > whenever we try to come up with something better than what > we have :( > > > It has wide reaching consequences as (with my irqchip maintainer hat on) > > we've had to pretend that some bits of HW (timers, interrupt > > controllers) are not "devices". Not a massive issue for most, except > > when your interrupt controller has requirements that are very similar to > > the DMA mapping API (which you cannot use because "not a device"). Other > > problems are introduced by things like wire-MSI bridges, and most people > > end-up resorting to hacks like ad-hoc initcalls and sprinkling deferred > > probes in specific drivers. > > Same feeling here. I'm accepting patches for random initcall > reordering because there is nothing else I can do, people need to > have their systems running. But it feels really fragile. > > Deferred probe alleviated the problem, but I remember saying at > the time that what we really need to do is build a dependency > graph and resolve it the same way e.g. systemd does. (Someone > may have called me BS on that, either for being wrong about everything > as usual or because of mentioning systemd, I don't know which one.) > > The latest proposal I saw came from Rafael and he had a scratch > idea for a dependency graph that I really liked, but I guess he's been > sidetracked since. Rafael, what happened with that? I got distracted, but Marek Szyprowski has revived it recently. It needs to be cleaned up somewhat, but other than that I think it's in a good enough shape to make some progress in that direction, at least in principle. Thanks, Rafael