From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932406AbbFRLDq (ORCPT ); Thu, 18 Jun 2015 07:03:46 -0400 Received: from terminus.zytor.com ([198.137.202.10]:58867 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932363AbbFRK4N (ORCPT ); Thu, 18 Jun 2015 06:56:13 -0400 Date: Thu, 18 Jun 2015 03:54:53 -0700 From: tip-bot for Feng Tang Message-ID: Cc: dvlasenk@redhat.com, akpm@linux-foundation.org, tglx@linutronix.de, bp@alien8.de, torvalds@linux-foundation.org, mingo@kernel.org, feng.tang@intel.com, hpa@zytor.com, peterz@infradead.org, brgerst@gmail.com, oleg@redhat.com, luto@amacapital.net, linux-kernel@vger.kernel.org Reply-To: hpa@zytor.com, peterz@infradead.org, brgerst@gmail.com, luto@amacapital.net, oleg@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, dvlasenk@redhat.com, akpm@linux-foundation.org, bp@alien8.de, torvalds@linux-foundation.org, mingo@kernel.org, feng.tang@intel.com In-Reply-To: <1434361201-31743-1-git-send-email-feng.tang@intel.com> References: <1434361201-31743-1-git-send-email-feng.tang@intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/platform] x86/platform/intel/baytrail: Add comments about why we disabled HPET on Baytrail Git-Commit-ID: b58d930750135d6c5b8e5aa084c0e9303c78c286 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b58d930750135d6c5b8e5aa084c0e9303c78c286 Gitweb: http://git.kernel.org/tip/b58d930750135d6c5b8e5aa084c0e9303c78c286 Author: Feng Tang AuthorDate: Mon, 15 Jun 2015 17:40:01 +0800 Committer: Ingo Molnar CommitDate: Thu, 18 Jun 2015 10:57:38 +0200 x86/platform/intel/baytrail: Add comments about why we disabled HPET on Baytrail This question has been asked many times, and finally I found the official document which explains the problem of HPET on Baytrail, that it will halt in deep idle states. Signed-off-by: Feng Tang Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: john.stultz@linaro.org Cc: len.brown@intel.com Cc: matthew.lee@intel.com Link: http://lkml.kernel.org/r/1434361201-31743-1-git-send-email-feng.tang@intel.com [ Prettified things a bit. ] Signed-off-by: Ingo Molnar --- arch/x86/kernel/early-quirks.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c index fe9f0b7..5cb9a4d 100644 --- a/arch/x86/kernel/early-quirks.c +++ b/arch/x86/kernel/early-quirks.c @@ -627,8 +627,12 @@ static struct chipset early_qrk[] __initdata = { { PCI_VENDOR_ID_INTEL, PCI_ANY_ID, PCI_CLASS_DISPLAY_VGA, PCI_ANY_ID, QFLAG_APPLY_ONCE, intel_graphics_stolen }, /* - * HPET on current version of Baytrail platform has accuracy - * problems, disable it for now: + * HPET on the current version of the Baytrail platform has accuracy + * problems: it will halt in deep idle state - so we disable it. + * + * More details can be found in section 18.10.1.3 of the datasheet: + * + * http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z8000-datasheet-vol-1.pdf */ { PCI_VENDOR_ID_INTEL, 0x0f00, PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet},