From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Zoltan Devai" Subject: Fwd: [PATCH] Fix PIT lockup on some chipsets when using the PC-Speaker Date: Thu, 6 Nov 2008 23:27:30 +0100 Message-ID: <5b7270f40811061427k4edecbbduf8edfe026baa9764@mail.gmail.com> References: <5b7270f40811021527j26c22d2ana3b5b9c437173989@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ey-out-2122.google.com ([74.125.78.27]:23874 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978AbYKFW1d (ORCPT ); Thu, 6 Nov 2008 17:27:33 -0500 Received: by ey-out-2122.google.com with SMTP id 6so401413eyi.37 for ; Thu, 06 Nov 2008 14:27:31 -0800 (PST) In-Reply-To: <5b7270f40811021527j26c22d2ana3b5b9c437173989@mail.gmail.com> Content-Disposition: inline Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: linux-input@vger.kernel.org Is this the right place for this patch ? The ALSA version is already in mainline. Zoltan ---------- Forwarded message ---------- From: Zoltan Devai Date: 2008/11/3 Subject: [PATCH] Fix PIT lockup on some chipsets when using the PC-Speaker To: linux-input@vger.kernel.org Hi, There've been reports [1] about the sysem bell causing a hard lockup. My machine was affected as well: Any speaker output hung the machine completely, nothing in the logs, no magic sysrq, etc., looked like a hardware problem. Had a closer look on the issue, and it turned out that the pcspkr module is responsible. The cause is the bad setup of Timer 2 in the i8253 controller, which probably hangs the whole PIT controller. Intel datasheets [2] state that the timer registers are in an undefined state after reset and they need to be programmed before enabling the timer. (And enabling without programming the frequency first doesn't make sense anyway). I don't know which chipsets are affected (if not all), it also depends on the BIOS whether it initializes the timer (e.g. to beep when you start the machine). The following patch solved the issue on my ICH6 notebook, couldn't test it with any others, but should be safe to apply. I'll also send a patch to the ALSA people for the snd-pcsp version. Cheers, Zoltan [1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/146151 https://bugs.launchpad.net/ubuntu/+bug/270790 http://ubuntuforums.org/showthread.php?t=227693 http://bugs.gentoo.org/show_bug.cgi?id=222583 https://bugzilla.redhat.com/show_bug.cgi?id=454225 [2] http://www.intel.com/assets/pdf/datasheet/252516.pdf http://www.intel.com/assets/pdf/datasheet/301473.pdf http://www.intel.com/design/chipsets/datashts/29065503.pdf ------------------ Fix PIT lockup on some chipsets when using the PC-Speaker. Signed-off-by: Zoltan Devai --- a/drivers/input/misc/pcspkr.c +++ b/drivers/input/misc/pcspkr.c @@ -52,13 +52,13 @@ spin_lock_irqsave(&i8253_lock, flags); if (count) { - /* enable counter 2 */ - outb_p(inb_p(0x61) | 3, 0x61); /* set command for counter 2, 2 byte write */ outb_p(0xB6, 0x43); /* select desired HZ */ outb_p(count & 0xff, 0x42); outb((count >> 8) & 0xff, 0x42); + /* enable counter 2 */ + outb_p(inb_p(0x61) | 3, 0x61); } else { /* disable counter 2 */ outb(inb_p(0x61) & 0xFC, 0x61);