linux-kernel - Re: [PATCH] x86/ACPI: Fix regression caused by 16ee7b3dcc56 & c50f13c672df7

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Date:	Sun, 12 Apr 2015 11:03:30 +0200
From:	Jim Bos <jim876@...all.nl>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-pm@...r.kernel.org
Subject: Re: [PATCH] x86/ACPI: Fix regression caused by 16ee7b3dcc56 & c50f13c672df7

On 04/12/2015 03:29 AM, Rafael J. Wysocki wrote:
> On Saturday, April 11, 2015 05:08:38 PM Jim Bos wrote:
>> On 04/10/2015 03:56 AM, Jiang Liu wrote:
>>> On 2015/4/10 0:41, Jim Bos wrote:
>>>> On 04/09/2015 12:15 PM, Jiang Liu wrote:
>>>>> On 2015/4/8 23:51, Jim Bos wrote:
>>>>>> On 04/08/2015 07:26 AM, Jiang Liu wrote:
>>>>>>> On 2015/4/8 0:49, Jim Bos wrote:
>>>>>>>> On 04/07/2015 04:34 PM, Jiang Liu wrote:
>>> <snip>
>>>>> Hi Jim,
>>>>> 	I'm really confused. I can't even explain why my previous
>>>>> patch fixes the issue on AMD geode board now:(
>>>>>
>>>>> For the Dell laptop, seems you have:
>>>>> 1) build a kernel with Local APIC and IOAPIC enabled
>>>>> 2) lapic is disabled by BIOS, so there's no ACPI MADT(APIC)
>>>>> table at all.
>>>>> That means the laptop is working with 8259 PICs only.
>>>>> There's little change between 3.16 and 4.0 related to 8259.
>>>>>
>>>>> For the AMD geode board, I still think original code is right.
>>>>> I can't explain why the patch fix the issue.
>>>>>
>>>>> So could you please help to:
>>>>> 1) Try to enable lapic on Dell laptop in BIOS
>>>>> 2) Dump acpi tables and dmesg on AMD board
>>>>>
>>>>> If that still doesn't help, I will try to send you some
>>>>> debug patches to gather more info.
>>>>> Thanks!
>>>>> Gerry
>>>>>> _
>>>>>> Jim
>>>>>>
>>>>>
>>>>
>>>> Gerry,
>>>>
>>>> As you mentioned your patch shouldn't make a difference, run some more
>>>> tests, as it turns out:
>>>> - geode system  broken on 3.16+ up to and including 3.19, however, on
>>>> plain 4.0-rc6 it works!  Root cause appears to be there isn't an ACPI
>>>> interrupt assigned in non-working kernels.
>>>> - other system I got my hands on: Pentium(R) CPU G3220, broken on 3.19.0
>>>> when boot parameter 'nosmp' is specified, again no acpi entry in
>>>> /proc/interrupts,  working fine on 4.0-rc6
>>>>
>>>> So obviously between 3.19 and 4.0-rc6 something got fixed here!
>>> Hi Jim,
>>> Yes, the bugfix patch should be:
>>> commit 1ea76fbadd66("x86/irq: Fix regression caused by commit b568b8601f05")
>>>
>>>> The Dell laptop remains the only problem then on 4.0-rc6, there IS an
>>>> acpi interrupt  (but firing once apparently).
>>>> There isn't an option in BIOS to enable LAPIC, however, when specifying
>>>> 'lapic' as boot parameter I got interesting result, still not working
>>>> and /proc/interrups still shows XT-PIC.  Doing a diff between dmesg on
>>>> 3.19 and 4.0-rc6 this pops out:
>>>>
>>>> -Local APIC disabled by BIOS -- you can enable it with "lapic"
>>>> -APIC: disable apic facility
>>>> -APIC: switched to apic NOOP
>>>> +Local APIC disabled by BIOS -- reenabling.
>>>> +Found and enabled local APIC!
>>>>
>>>> +Enabling APIC mode:  Flat.  Using 0 I/O APICs
>>> What's the last know working kernel for Dell laptop?
>>> Does it work as expected with v3.19 kernel?
>>> Do you means this message is from plain v4.0-rc6 kernel?
>>> Thanks!
>>> Gerry
>>>
>>>>
>>>> Jim
>>>>
>>>
>>
>> Gerry, Rafael,
>>
>> Ok, found it.
>> It was very 'interesting' bisect, because there were 2 overlapping
>> issues here.  On the Dell laptop some kernels there wasn't an ACPI
>> interrupt at all or it fired once and then seemed to get stuck.
>> Turns out that kernel version:
>> 3.16: OK
>> 3.17: Broken (no acpi interrupt)
>> 3.18: actually fine
>> 3.19: Broken
>>
>> So started bisecting between 3.18 or 3.19, in the end found Rafael's
>> patch which broke it:
>>
>> ==
>> commit c50f13c672df758b59e026c15b9118f3ed46edc4
>> Author: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>> Date:   Mon Dec 1 23:50:16 2014 +0100
>>
>>     ACPICA: Save current masks of enabled GPEs after enable register writes
>> ==
>>
>> Reverting that patch on top of 4.0-rc7 (with some offsets and one
>> trivial manual edit) and I finally got a working ACPI interrupt again!
> 
> That's unexpected.
> 
> Is system suspend/resume involved in the reproduction of the problem in any way?
> 
> In any case, does it help if you replace "enable_mask" with "enable_for_run"
> in line 127 of drivers/acpi/acpica/hwgpe.c (without reverting the whole commit)?
> 
> 

No suspends/resumes, but this suggestion works :-)


--- hwgpe.c.ORIG        2015-04-12 10:41:11.754104398 +0200
+++ hwgpe.c     2015-04-12 10:42:38.021283593 +0200
@@ -124,7 +124,7 @@

                /* Only enable if the corresponding enable_mask bit is
set */

-               if (!(register_bit & gpe_register_info->enable_mask)) {
+               if (!(register_bit & gpe_register_info->enable_for_run)) {
                        return (AE_BAD_PARAMETER);
                }

Tested-by: Jim Bos <jim876@...all.nl>

Thanks,
Jim

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