From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754760Ab3ADNgk (ORCPT ); Fri, 4 Jan 2013 08:36:40 -0500 Received: from h1446028.stratoserver.net ([85.214.92.142]:38700 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754671Ab3ADNgi (ORCPT ); Fri, 4 Jan 2013 08:36:38 -0500 Message-ID: <50E6DAC9.802@ahsoftware.de> Date: Fri, 04 Jan 2013 14:36:09 +0100 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Alan Cox CC: Borislav Petkov , Shawn Guo , Sasha Levin , Cong Wang , Josh Boyer , LKML , Florian Tobias Schandinat , Linus Torvalds , linux-fbdev@vger.kernel.org, Bernie Thompson , Steve Glendinning , Dave Airlie Subject: Re: [PATCH] fb: Rework locking to fix lock ordering on takeover References: <20121116192606.11799.35711.stgit@localhost.localdomain> <20121121125310.00625f55@pyramind.ukuu.org.uk> <20121227045301.GB17472@x1.alien8.de> <20121228115022.GA28009@S2101-09.ap.freescale.net> <20121228124026.GB12918@x1.alien8.de> <50E6D01D.6040304@ahsoftware.de> <20130104132557.70e0c527@pyramind.ukuu.org.uk> In-Reply-To: <20130104132557.70e0c527@pyramind.ukuu.org.uk> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 04.01.2013 14:25, schrieb Alan Cox: > On Fri, 04 Jan 2013 13:50:37 +0100 > Alexander Holler wrote: > >> Am 28.12.2012 13:40, schrieb Borislav Petkov: >>> On Fri, Dec 28, 2012 at 07:50:27PM +0800, Shawn Guo wrote: >>>> +1 >>>> >>>> http://thread.gmane.org/gmane.linux.kernel/1413953/focus=1415070 >>> >>> Cool, works fine here too. Is Linus on CC? (/me checks.. ) Yes he is, >>> good. >>> >>> Linus, Alan's patch works at least in 2 cases, you might consider >>> picking it up directly since the fb maintainer is absent, reportedly. >> >> >> Btw. I think all the usb-fb's (udlfb, smscufx and udl) are broken, at >> least on ARM(v5). When I have linked in udlfb the following happens on >> boot (with an attached USB-LCD and with or without the "Rework locking >> patch): > > They are broken if used as the system console (has been known for years). Ah. Thats why I didn't see it before. Usually I've used the serial as system console. So thats why it worked before. ;) > Perhaps your x86 test has the system console still on another device ? Exactly thats the case. Thanks for pointing it out. > For the udl layer it shouldn't matter as Dave Airlie wrote a DRM driver > for udl which obsoletes the old fb layer one and works much better > (although the error handling is still totally broken and leaks like a > sieve if it fails) > > Fixing the console isn't that difficult - you just need to make your > device queue the console I/O to a worker thread of some kind. We don't That is what I wanted to try next. ;) > want to do that by default because we want to get the messages out > reliably and immediately on saner hardware. Given there are several > such cases a general helper and a console "I am crap" flag might be better > than hacking each driver. All those drivers look very similiar. I will see if I'm successfull in writing such an IamCrapHelper. Might need some time, but I will post a patch for review, if I've done and tested it. I'm only using the USB-LCD on occasion, so it doesn't have high priority for me because I don't really need it. Thanks for the hints. Regards, Alexander