linux-kernel - Re: [RFC PATCH] PCIe: Add PCIe runtime D3cold support

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Date:	Wed, 18 Apr 2012 09:22:20 +0800
From:	huang ying <huang.ying.caritas@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	"Yan, Zheng" <zheng.z.yan@...el.com>, bhelgaas@...gle.com,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-pm@...r.kernel.org, Lin Ming <ming.m.lin@...el.com>,
	Zhang Rui <rui.zhang@...el.com>,
	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>
Subject: Re: [RFC PATCH] PCIe: Add PCIe runtime D3cold support

On Wed, Apr 18, 2012 at 4:43 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Tuesday, April 17, 2012, huang ying wrote:
>> On Tue, Apr 17, 2012 at 10:12 AM, Yan, Zheng <zheng.z.yan@...el.com> wrote:
>> > On 04/17/2012 01:07 AM, Rafael J. Wysocki wrote:
>> >
>> >> BTW, can you please explain to me what the #WAKE signal is and how it is
>> >> different from PME#?
>> >
>> > #WAKE signal is triggered by a pin connected to the root complex or other
>> > motherboard logic. PME# is triggered by PME message sent to the port.
>>
>> PME# is a PCI pin, while WAKE# is a PCI Express pin.  In PCI Express,
>> there is no PME#, PME is delivered between end point device and root
>> port or root complex event collector via PME message, and the PME
>> message will trigger IRQ on root port or root complex event collector.
>>  WAKE# is not used for PCI Express D1, D2 and D3hot, it is just used
>> by D3cold.  When remote wakeup detected by end point device, it will
>> assert WAKE# to notify power controller (implemented via ACPI on some
>> platform), then power controller will turn on power for main link,
>> after link goes back to L0, PME message will be sent to root port or
>> root complex event collector by end point device.
>
> OK
>
> So do I understand correctly that the WAKE# signal here is the one described
> in Section 5.3.3.2 Link Wakeup of PCI Express Base spec. 2.0?
>
> So what happens is that it triggers a GPE and that GPE has a _Lxx method
> associated with it, I suppose.  Is that correct?

Yes.

Best Regards,
Huang Ying
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