From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [PATCH v2 1/5] irqchip: add dumb demultiplexer implementation Date: Tue, 20 Jan 2015 14:08:53 +0100 (CET) Message-ID: References: <1421174781-4340-1-git-send-email-boris.brezillon@free-electrons.com> <1421174781-4340-2-git-send-email-boris.brezillon@free-electrons.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Rob Herring Cc: Boris Brezillon , Jason Cooper , Nicolas Ferre , Jean-Christophe Plagniol-Villard , Alexandre Belloni , "Rafael J. Wysocki" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , "devicetree@vger.kernel.org" List-Id: devicetree@vger.kernel.org On Thu, 15 Jan 2015, Rob Herring wrote: > On Thu, Jan 15, 2015 at 3:11 AM, Thomas Gleixner wrote: > > On Wed, 14 Jan 2015, Rob Herring wrote: > > > We do not change shared interrupts in any way. We provide an > > alternative mechanism for braindead hardware. And if the at91 folks > > are fine with the DT change, then it's their decision. Nothing forces > > this on everyone. > > We are changing how shared interrupts are described in DT. We don't > need 2 ways to describe them. We could say this is only for AT91 and > continue to describe shared interrupts as has been done forever. Then > the next platform that hits this problem will have to go thru the same > ABI breakage. Or we change DT practices to describe all shared > interrupts with a demux node. Given the way DTs are incrementally > created, it is not something we can check with review or tools, so we > will still have the same ABI breakage problem. This is not describing the proper shared interrupts. This is a special case for a special case of braindamaged hardware. Whats wrong with doing that? We dont have to change that for all shared interrupts because 99% of them have a proper hardware implementation and are not affected by this. What's wrong with serving the AT91 with a proper solution, which does NOT inflict horrible hacks into the core code and does NOT weaken sanity checks and does NOT require irq chip specific knowledge in device drivers? > >> There are probably ways to do this demux irqchip without a DT change. So far you have not provided any useful hint how to do so. > > What's the problem with a DT change for a single platform, if the > > maintainers are willing to take it and deal with the fallout? > > What's the solution for a platform that an ABI break is not okay and > can't deal with the fallout? There is no other platform affected. This is a break for a specific set of devices and the 'fallout' is confined, well known and accepted. So what's your problem, really? Thanks, tglx