From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752311AbbHBJKp (ORCPT <rfc822;w@1wt.eu>);
	Sun, 2 Aug 2015 05:10:45 -0400
Received: from www.linutronix.de ([62.245.132.108]:57586 "EHLO
	Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751853AbbHBJKn (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Sun, 2 Aug 2015 05:10:43 -0400
Date: Sun, 2 Aug 2015 11:10:21 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Alexandre Belloni <alexandre.belloni@free-electrons.com>
cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
        Nicolas Ferre <nicolas.ferre@atmel.com>,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        LAK <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        David Dueck <davidcdueck@googlemail.com>,
        Sebastian Sewior <bigeasy@linutronix.de>
Subject: Re: [PATCH 1/3] clocksource: atmel-st: Remove irq handler when clock
 event is unused
In-Reply-To: <alpine.DEB.2.11.1507202245310.18576@nanos>
Message-ID: <alpine.DEB.2.11.1508021100390.3825@nanos>
References: <1437161608-26782-1-git-send-email-alexandre.belloni@free-electrons.com> <1437161608-26782-2-git-send-email-alexandre.belloni@free-electrons.com> <alpine.DEB.2.11.1507180942360.18576@nanos> <20150718222308.GA30489@piout.net>
 <alpine.DEB.2.11.1507201103550.18576@nanos> <20150720193726.GJ15539@piout.net> <alpine.DEB.2.11.1507202245310.18576@nanos>
User-Agent: Alpine 2.11 (DEB 23 2013-08-11)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-Linutronix-Spam-Score: -1.0
X-Linutronix-Spam-Level: -
X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required,  ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, 20 Jul 2015, Thomas Gleixner wrote:

> On Mon, 20 Jul 2015, Alexandre Belloni wrote:
> 
> > On 20/07/2015 at 11:04:30 +0200, Thomas Gleixner wrote :
> > > That's why I used setup/remove_irq() in the stale RT changes.
> > > 
> > 
> > Hum, actually, you hit the same thing with setup/remove_irq (and I'm not sure
> > to follow why):
> 
> It's the kmalloc of the proc interface. So back to the drawing
> board. I'll think about it tomorrow with brain awake.

So the only idea I could come up with is the old approach of creating
a dummy irq chip for the interrupts which share that timer/uart/rtc
whatever line.

I think Boris Brezillon had implemented it at some point, but it was
shot down for reasons I can't remember. That would allow us to simply
have disable_irq_nosync/enable_irq in the relevant code pathes and be
done with it. I guess I need to find the references and give it a try
again if nobody beats me to it.

Thanks,

	tglx