From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752795AbdJLP3e (ORCPT ); Thu, 12 Oct 2017 11:29:34 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:38833 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492AbdJLP3d (ORCPT ); Thu, 12 Oct 2017 11:29:33 -0400 Date: Thu, 12 Oct 2017 17:29:23 +0200 (CEST) From: Thomas Gleixner To: Daniel Lezcano cc: David Kozub , linux-kernel@vger.kernel.org Subject: Re: PROBLEM: Kernel BUG in mfgpt_tick (cs5535-clockevt.c) on ALIX 2c3 - null call In-Reply-To: Message-ID: References: <8de07c60-8d37-802a-837c-a6cf356d1535@linaro.org> <29c0b5e6-3285-a307-4045-6b2b9f9747d6@linaro.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-1767809671-1507822171=:1930" 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: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1767809671-1507822171=:1930 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT On Thu, 12 Oct 2017, Daniel Lezcano wrote: > On 11/10/2017 22:48, David Kozub wrote: > > [ ... ] > > >> > >> +       disable_timer(timer); > >> +       cs5535_mfgpt_write(timer, MFGPT_REG_COUNTER, 0); > >> + > >>        /* Set up the IRQ on the MFGPT side */ > >>        if (cs5535_mfgpt_setup_irq(timer, MFGPT_CMP2, &timer_irq)) { > >>                printk(KERN_ERR DRV_NAME ": Could not set up IRQ %d\n", > > > > I tried that and the handler is still called. So I did some more random > > experiments and I found out that if I call disable_timer(timer) twice, > > then the issue is resolved (the handler is not called before the > > registration is finished.) And I don't have to set MFGPT_REG_COUNTER to 0. > > Aha! we are close to a fix. > > > I have no idea why do I have to call disable_timer twice. > > For testing purpose, can you try by adding mmiowb() and/or wmb() after > disable_timer()? The real question is why /* Set the clock scale and enable the event mode for CMP2 */ val = MFGPT_SCALE | (3 << 8); cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_SETUP, val); is in the setup code at all. The obvious place for this is in mfgpt_set_periodic() which gets called when the clock event and the handler is set up in the core code. Up to that point the interrupt handler is protected against shared interrupts via the is_shutdown() check. Thanks, tglx --8323329-1767809671-1507822171=:1930--