Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757395AbdCUMUZ (ORCPT ); Tue, 21 Mar 2017 08:20:25 -0400 Received: from terminus.zytor.com ([65.50.211.136]:46638 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757380AbdCUMUV (ORCPT ); Tue, 21 Mar 2017 08:20:21 -0400 Date: Tue, 21 Mar 2017 05:19:25 -0700 From: tip-bot for Lu Baolu Message-ID: Cc: bp@alien8.de, dvlasenk@redhat.com, tglx@linutronix.de, peterz@infradead.org, brgerst@gmail.com, mathias.nyman@linux.intel.com, mingo@kernel.org, hpa@zytor.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, jpoimboe@redhat.com, luto@kernel.org, torvalds@linux-foundation.org, baolu.lu@linux.intel.com Reply-To: brgerst@gmail.com, mathias.nyman@linux.intel.com, dvlasenk@redhat.com, tglx@linutronix.de, peterz@infradead.org, bp@alien8.de, luto@kernel.org, torvalds@linux-foundation.org, baolu.lu@linux.intel.com, hpa@zytor.com, jpoimboe@redhat.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org In-Reply-To: <1490083293-3792-2-git-send-email-baolu.lu@linux.intel.com> References: <1490083293-3792-2-git-send-email-baolu.lu@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/debug] x86/timers: Add simple udelay calibration Git-Commit-ID: dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b 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 Content-Length: 2325 Lines: 73 Commit-ID: dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b Gitweb: http://git.kernel.org/tip/dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b Author: Lu Baolu AuthorDate: Tue, 21 Mar 2017 16:01:29 +0800 Committer: Ingo Molnar CommitDate: Tue, 21 Mar 2017 12:28:45 +0100 x86/timers: Add simple udelay calibration Add a simple udelay calibration in x86 architecture-specific boot-time initializations. This will get a workable estimate for loops_per_jiffy. Hence, udelay() could be used after this initialization. Signed-off-by: Lu Baolu Acked-by: Thomas Gleixner Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Greg Kroah-Hartman Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Mathias Nyman Cc: Peter Zijlstra Cc: linux-usb@vger.kernel.org Link: http://lkml.kernel.org/r/1490083293-3792-2-git-send-email-baolu.lu@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/setup.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 4bf0c89..e70204e 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -837,6 +837,26 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p) return 0; } +static void __init simple_udelay_calibration(void) +{ + unsigned int tsc_khz, cpu_khz; + unsigned long lpj; + + if (!boot_cpu_has(X86_FEATURE_TSC)) + return; + + cpu_khz = x86_platform.calibrate_cpu(); + tsc_khz = x86_platform.calibrate_tsc(); + + tsc_khz = tsc_khz ? : cpu_khz; + if (!tsc_khz) + return; + + lpj = tsc_khz * 1000; + do_div(lpj, HZ); + loops_per_jiffy = lpj; +} + /* * Determine if we were loaded by an EFI loader. If so, then we have also been * passed the efi memmap, systab, etc., so we should use these data structures @@ -985,6 +1005,8 @@ void __init setup_arch(char **cmdline_p) */ x86_configure_nx(); + simple_udelay_calibration(); + parse_early_param(); #ifdef CONFIG_MEMORY_HOTPLUG