Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751601AbdHXJ2W (ORCPT ); Thu, 24 Aug 2017 05:28:22 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:22235 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751259AbdHXJ2U (ORCPT ); Thu, 24 Aug 2017 05:28:20 -0400 X-IronPort-AV: E=Sophos;i="5.41,420,1498492800"; d="scan'208";a="24629298" Subject: Re: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization earlier To: Baoquan He References: <1500011554-9784-1-git-send-email-douly.fnst@cn.fujitsu.com> <1500011554-9784-13-git-send-email-douly.fnst@cn.fujitsu.com> <8d662105-2ff5-02fd-9072-73167e5f49c1@cn.fujitsu.com> <20170824080528.GD19768@x1> CC: , , "Rafael J. Wysocki" , "Zheng, Lv" , , , , , , , , , Julian Wollrath , Borislav Petkov From: Dou Liyang Message-ID: <6b800d1a-d924-6dec-8c3e-299e4a67ed68@cn.fujitsu.com> Date: Thu, 24 Aug 2017 17:28:01 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20170824080528.GD19768@x1> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.106] X-yoursite-MailScanner-ID: F0D374724001.AA81A X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: douly.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4364 Lines: 162 Hi Baoquan, Thanks for your reply. At 08/24/2017 04:05 PM, Baoquan He wrote: > Hi Liyang, > > On 08/24/17 at 11:54am, Dou Liyang wrote: >>>> Test in my own PC(Lenovo M4340). >>>> Ask help for doing regression testing for the bug said in commit >>>> c4e1acbb35e4 >>>> ("ACPI / init: Invoke early ACPI initialization later"). >>>> >>> >>> Now, I can prove this patch doesn't result in the bug[1] which made the >>> fast TSC calibration using PIT failed in a Thinkpad x121e (AMD E-450 >>> APU). >>> >>> The true reason of the bug is enabling ACPI subsystem earlier than >>> using PIT, not the SCI setup. invoking acpi_enable_subsystem() later > > Seems redhat mail server was down earlier, I didn't receive new mail in > this thread. Just curious, do you know why the fast tsc calibration > using PIT will fail if enabling ACPI subsystem earlier than using PIT? > It's related to particular hardware, As you know, I tested in many kinds of PC and laptop and PIT works well no matter before or after enabling ACPI subsystem. In pit_verify_msb(), we use inb(0x42) to read the current MSB, Normally, the value is continuously, like following shows: msb = fe msb = fd msb = fc msb = fb msb = fa msb = f9 msb = f8 msb = f7 msb = f6 ... But, if in some particular hardware, you will see like that: msb = fe msb = f0 msb = ed msb = e9 msb = e0 msb = db ... In this case, the count in pit_expect_msb() is always zero. So we will see "Fast TSC calibration failed" in our dmesg log. For the further deep reason why the hardware failed, I'm sorry I can't answer and don't know how to investigate. For hardware, I usually change a new one directly and know very little. Thanks, dou. > Thanks > Baoquan > >>> could fix this bug as Julian tested and said[2]. >>> >>> And, I found that Commit b064a8fa77df (" ACPI / init: Switch over >>> platform to the ACPI mode later") split the ACPI early initialization >>> code into acpi_early_init() and acpi_subsystem_init(). executing >>> acpi_enable_subsystem() at the original early ACPI initialization spot. >>> >>> The sequence of them shows below: >>> >>> start_kernel >>> +---------------+ >>> | >>> +--> ....... >>> | >>> | late_time_init() >>> +--> +-------+ >>> | >>> +--> ....... >>> | >>> | acpi_early_init() >>> +--> +-------+ >>> | >>> +--> ....... >>> | >>> | acpi_subsystem_init() >>> +-> +--------+ >>> >>> We make sure the acpi_subsystem_init() is called later than >>> late_time_init(), the bug will be avoided. >>> >>> This patch changes the sequence of late_time_init() and >>> acpi_early_init(), doesn't effect acpi_subsystem_init(). >>> >>> So, this patch is OK. >>> >>> Btw, Thanks very much for Borislav Petkov, he will have access to >>> Thinkpad x121e from Mid-August and will test this series. >>> >> >> Almost one month passed, Borislav have tested this series in Thinkpad >> x121e and I also have tested in my box and QEmu again. It is OK. >> >> BTW, >> 1) I found your commit b064a8fa77df (" ACPI / init: Switch over >> platform to the ACPI mode later") split the ACPI early initialization >> code into acpi_early_init() and acpi_subsystem_init(). Actually enabling >> the ACPI subsystem is in acpi_subsystem_init(). >> >> 2) As we discussed earlier, invoking acpi_put_table() is not good for >> this situation. >> >> So I do this patch, Is that goot to you? Any comments will be welcome. >> >> If it is OK, As the patches need to be re-based, and I also found >> several spelling mistake, I will send a new version next week. >> >> Thanks, >> dou. >> >>> [1] https://lkml.org/lkml/2014/3/10/123 >>> [2] https://lkml.org/lkml/2014/3/12/311 >>> >>> >>> Thanks >>> dou. >>> >>>> init/main.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/init/main.c b/init/main.c >>>> index df58a41..7a09467 100644 >>>> --- a/init/main.c >>>> +++ b/init/main.c >>>> @@ -654,12 +654,12 @@ asmlinkage __visible void __init start_kernel(void) >>>> kmemleak_init(); >>>> setup_per_cpu_pageset(); >>>> numa_policy_init(); >>>> + acpi_early_init(); >>>> if (late_time_init) >>>> late_time_init(); >>>> calibrate_delay(); >>>> pidmap_init(); >>>> anon_vma_init(); >>>> - acpi_early_init(); >>>> #ifdef CONFIG_X86 >>>> if (efi_enabled(EFI_RUNTIME_SERVICES)) >>>> efi_enter_virtual_mode(); >>>> >> >> > > >