linux-kernel - Re: [PATCH v2] x86: Bypass legacy PIC and PIT in ACPI hardware reduced mode

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Date:	Wed, 11 Mar 2015 15:51:36 +0800
From:	"Li, Aubrey" <aubrey.li@...ux.intel.com>
To:	Ingo Molnar <mingo@...nel.org>
CC:	Ingo Molnar <mingo@...hat.com>,
	"alan@...ux.intel.com" <alan@...ux.intel.com>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Brown, Len" <len.brown@...el.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>, x86@...nel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86: Bypass legacy PIC and PIT in ACPI hardware reduced
 mode

On 2015/3/11 14:23, Ingo Molnar wrote:
> 
> * Li, Aubrey <aubrey.li@...ux.intel.com> wrote:
> 
>> On a platform in ACPI Hardware-reduced mode, the legacy PIC and PIT
>> may not be initialized even though they may be present in silicon.
>> Touching these legacy components causes unexpected result on system.
> 
> s/causes unexpected result on system/
>   causes unexpected results on the system
> 
>>
>> On Bay Trail-T(ASUS-T100) platform, touching these legacy components
> 
> s/On Bay Trail-T(ASUS-T100) platform/
>   On the Bay Trail-T(ASUS-T100) platform
> 
> Ok, my final bike shed painting job would be to move the 
> 'acpi_gbl_reduced_hardware' flag check inside acpi_reduced_hw_init(): 
> that makes it nicely self-sustained and all in a single place.
> 
> With that fixed it looks good to me.

Thanks, I'll cook v3 soon, :-)
> 
> Should I merge it for v4.0 upstream merge, in tip:x86/urgent?
> 
> The 'touches hardware in unexpected ways' aspect qualifies it for 
> urgent treatment IMO.

Currently the unexpected result is that it blocks a low power idle
during suspend. I'm not sure if it can be for x86/urgent. But it would
be nice if it can be a bug-fix in v4.0.

Thanks,
-Aubrey

> 
> Thanks,
> 
> 	Ingo
> 
> 

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