Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757140AbZDVOC2 (ORCPT ); Wed, 22 Apr 2009 10:02:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756174AbZDVNzT (ORCPT ); Wed, 22 Apr 2009 09:55:19 -0400 Received: from hera.kernel.org ([140.211.167.34]:49785 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755797AbZDVNzR (ORCPT ); Wed, 22 Apr 2009 09:55:17 -0400 Date: Wed, 22 Apr 2009 13:54:30 GMT From: tip-bot for Andreas Herrmann To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, andreas.herrmann3@amd.com, jeffm@suse.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, andreas.herrmann3@amd.com, jeffm@suse.com, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20090421180037.GA2763@alberich.amd.com> References: <20090421180037.GA2763@alberich.amd.com> Subject: [tip:x86/urgent] x86: hpet: fix periodic mode programming on AMD 81xx Message-ID: Git-Commit-ID: 7a6f9cbb37120c745fc187083fb5c3de4dca4f97 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 22 Apr 2009 13:54:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3419 Lines: 96 Commit-ID: 7a6f9cbb37120c745fc187083fb5c3de4dca4f97 Gitweb: http://git.kernel.org/tip/7a6f9cbb37120c745fc187083fb5c3de4dca4f97 Author: Andreas Herrmann AuthorDate: Tue, 21 Apr 2009 20:00:37 +0200 Committer: Ingo Molnar CommitDate: Wed, 22 Apr 2009 15:53:40 +0200 x86: hpet: fix periodic mode programming on AMD 81xx (See http://bugzilla.kernel.org/show_bug.cgi?id=12961) It partially reverts commit c23e253e67c9d8a91a0ffa33c1f571a17f0a2403 (x86: hpet: stop HPET_COUNTER when programming periodic mode) HPET on AMD 81xx chipset needs a second write (with HPET_TN_SETVAL cleared) to T0_CMP register to set the period in periodic mode. With this patch HPET_COUNTER is still stopped but not reset when HPET is programmed in periodic mode. This should help to avoid races when HPET is programmed in periodic mode and fixes a boot time hang that I've observed on a machine when using 1000HZ. [ Impact: fix boot time hang on machines with AMD 81xx chipset ] Reported-by: Jeff Mahoney Signed-off-by: Andreas Herrmann Tested-by: Jeff Mahoney LKML-Reference: <20090421180037.GA2763@alberich.amd.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/hpet.c | 18 +++++++++++++++++- 1 files changed, 17 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 3f0019e..81408b9 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -236,6 +236,10 @@ static void hpet_stop_counter(void) unsigned long cfg = hpet_readl(HPET_CFG); cfg &= ~HPET_CFG_ENABLE; hpet_writel(cfg, HPET_CFG); +} + +static void hpet_reset_counter(void) +{ hpet_writel(0, HPET_COUNTER); hpet_writel(0, HPET_COUNTER + 4); } @@ -250,6 +254,7 @@ static void hpet_start_counter(void) static void hpet_restart_counter(void) { hpet_stop_counter(); + hpet_reset_counter(); hpet_start_counter(); } @@ -309,7 +314,7 @@ static int hpet_setup_msi_irq(unsigned int irq); static void hpet_set_mode(enum clock_event_mode mode, struct clock_event_device *evt, int timer) { - unsigned long cfg; + unsigned long cfg, cmp, now; uint64_t delta; switch (mode) { @@ -317,12 +322,23 @@ static void hpet_set_mode(enum clock_event_mode mode, hpet_stop_counter(); delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * evt->mult; delta >>= evt->shift; + now = hpet_readl(HPET_COUNTER); + cmp = now + (unsigned long) delta; cfg = hpet_readl(HPET_Tn_CFG(timer)); /* Make sure we use edge triggered interrupts */ cfg &= ~HPET_TN_LEVEL; cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL | HPET_TN_32BIT; hpet_writel(cfg, HPET_Tn_CFG(timer)); + hpet_writel(cmp, HPET_Tn_CMP(timer)); + udelay(1); + /* + * HPET on AMD 81xx needs a second write (with HPET_TN_SETVAL + * cleared) to T0_CMP to set the period. The HPET_TN_SETVAL + * bit is automatically cleared after the first write. + * (See AMD-8111 HyperTransport I/O Hub Data Sheet, + * Publication # 24674) + */ hpet_writel((unsigned long) delta, HPET_Tn_CMP(timer)); hpet_start_counter(); hpet_print_config(); -- 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/