Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934741AbXEUTld (ORCPT ); Mon, 21 May 2007 15:41:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933612AbXEUT1W (ORCPT ); Mon, 21 May 2007 15:27:22 -0400 Received: from 216-99-217-87.dsl.aracnet.com ([216.99.217.87]:35810 "EHLO sous-sol.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933602AbXEUT1T (ORCPT ); Mon, 21 May 2007 15:27:19 -0400 Message-Id: <20070521191740.534306000@sous-sol.org> References: <20070521191612.800400000@sous-sol.org> User-Agent: quilt/0.46-1 Date: Mon, 21 May 2007 12:16:55 -0700 From: Chris Wright To: linux-kernel@vger.kernel.org, stable@kernel.org, Andi Kleen Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Thomas Gleixner , guilherme@centralinf.com.br, johnstul@us.ibm.com Subject: [patch 43/69] i386: HPET, check if the counter works Content-Disposition: inline; filename=i386-hpet-check-if-the-counter-works.patch Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1668 Lines: 64 -stable review patch. If anyone has any objections, please let us know. --------------------- From: Thomas Gleixner Some systems have a HPET which is not incrementing, which leads to a complete hang. Detect it during HPET setup. Signed-off-by: Thomas Gleixner Signed-off-by: Chris Wright --- [chrisw: Why is this not upstream yet?] --- arch/i386/kernel/hpet.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) --- linux-2.6.21.1.orig/arch/i386/kernel/hpet.c +++ linux-2.6.21.1/arch/i386/kernel/hpet.c @@ -226,7 +226,8 @@ int __init hpet_enable(void) { unsigned long id; uint64_t hpet_freq; - u64 tmp; + u64 tmp, start, now; + cycle_t t1; if (!is_hpet_capable()) return 0; @@ -273,6 +274,27 @@ int __init hpet_enable(void) /* Start the counter */ hpet_start_counter(); + /* Verify whether hpet counter works */ + t1 = read_hpet(); + rdtscll(start); + + /* + * We don't know the TSC frequency yet, but waiting for + * 200000 TSC cycles is safe: + * 4 GHz == 50us + * 1 GHz == 200us + */ + do { + rep_nop(); + rdtscll(now); + } while ((now - start) < 200000UL); + + if (t1 == read_hpet()) { + printk(KERN_WARNING + "HPET counter not counting. HPET disabled\n"); + goto out_nohpet; + } + /* Initialize and register HPET clocksource * * hpet period is in femto seconds per cycle -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/