From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752723AbdAZD0k (ORCPT ); Wed, 25 Jan 2017 22:26:40 -0500 Received: from mga06.intel.com ([134.134.136.31]:16117 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576AbdAZD0j (ORCPT ); Wed, 25 Jan 2017 22:26:39 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,287,1477983600"; d="scan'208";a="52508051" Subject: Re: [PATCH v5 1/4] usb: dbc: early driver for xhci debug capability To: Ingo Molnar References: <1479189731-2728-1-git-send-email-baolu.lu@linux.intel.com> <1479189731-2728-2-git-send-email-baolu.lu@linux.intel.com> <20170119093743.GC22865@gmail.com> <58817A25.6080305@linux.intel.com> <20170122090423.GA15061@gmail.com> <5886DBB7.4070501@linux.intel.com> <20170124082039.GB8667@gmail.com> <5888377F.8090709@linux.intel.com> <20170125092355.GA24580@gmail.com> Cc: Greg Kroah-Hartman , Mathias Nyman , Ingo Molnar , tglx@linutronix.de, peterz@infradead.org, linux-usb@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Jiri Slaby From: Lu Baolu Message-ID: <58896C6D.8080705@linux.intel.com> Date: Thu, 26 Jan 2017 11:26:37 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20170125092355.GA24580@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ingo, On 01/25/2017 05:23 PM, Ingo Molnar wrote: > * Lu Baolu wrote: > >>> Hiding essentially an early udelay() implementation in an early-printk driver is >>> ugly and counterproductive. >> Sure. How about below change? >> >> diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c >> index d3f0c84..940989e 100644 >> --- a/drivers/usb/early/xhci-dbc.c >> +++ b/drivers/usb/early/xhci-dbc.c >> @@ -587,6 +587,35 @@ static int xdbc_bulk_transfer(void *data, int size, bool read) >> return size; >> } >> >> +static void __init xdbc_udelay_calibration(void) >> +{ >> + unsigned long lpj = 0; >> + unsigned int tsc_khz, cpu_khz; >> + >> + if (!boot_cpu_has(X86_FEATURE_TSC)) >> + goto calibration_out; >> + >> + cpu_khz = x86_platform.calibrate_cpu(); >> + tsc_khz = x86_platform.calibrate_tsc(); >> + >> + if (tsc_khz == 0) >> + tsc_khz = cpu_khz; >> + else if (abs(cpu_khz - tsc_khz) * 10 > tsc_khz) >> + cpu_khz = tsc_khz; >> + >> + if (!tsc_khz) >> + goto calibration_out; >> + >> + lpj = tsc_khz * 1000; >> + do_div(lpj, HZ); >> + >> +calibration_out: >> + if (!lpj) >> + lpj = 1 << 22; >> + >> + loops_per_jiffy = lpj; >> +} >> + >> static int __init xdbc_early_setup(void) >> { >> int ret; >> @@ -686,6 +715,8 @@ int __init early_xdbc_parse_parameter(char *s) >> } >> xdbc.xdbc_reg = (struct xdbc_regs __iomem *)(xdbc.xhci_base + offset); >> >> + xdbc_udelay_calibration(); >> + >> return 0; >> } > Yeah - so could we do this in a more generic fashion, not in the early-printk > driver but in core x86 code? How about below changes? diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 4cfba94..aab7faa 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -835,6 +835,26 @@ 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 @@ -983,6 +1003,8 @@ void __init setup_arch(char **cmdline_p) */ x86_configure_nx(); + simple_udelay_calibration(); + parse_early_param(); If it's okay for you, do you want it in a separated patch or part of patch 2/4? Best regards, Lu Baolu