linux-kernel - Re: [PATCH] ACPI / PCI: Make _SxD/

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Date:	Tue, 01 May 2012 18:27:17 +0200
From:	"Oleksij Rempel (fishor)" <bug-track@...her-privat.net>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Len Brown <lenb@...nel.org>,
	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	linux-pci@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Andrey Rahmatullin <wrar@...r.name>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] ACPI / PCI: Make _SxD/_SxW check follow ACPI 4.0a spec

On 01.05.2012 16:11, Alan Stern wrote:
> On Tue, 1 May 2012, Rafael J. Wysocki wrote:
>
>>> I mean not just the mapping.
>>> I mean PCI:PME_SUP field.  If it PME(D0+,D1-,D2-,D3hot+,D3cold+), and
>>> acpi trying to avoid D3 states for this device. then is is same like
>>> PME(D0+,D1-,D2-)? Or not?
>>
>> Yes, if _S3D or _S3W are present.  If they are not present and _PRW is,
>> that means "don't care".
>>
>>> According to spec.:
>>> 7.2 Device Power Management Objects (page 287)
>>> _S3D - Highest D-state supported by the device in the S3 state
>>> _S3W - Lowest D-state supported by the device in the S3 state which can
>>> wake the system.
>>> by definition if _S3W is specified then we can assume, the device can
>>> wake? But _SxW is not defined.
>>
>> The device can wake up the system if _PRW is present for it (and for
>> PCIe devices even that is not formally necessary).
>>
>>> Are there any other method to forbid the system use broken state, after
>>> device was actually produced? Usual BIOS flash utility will probably no
>>> rewrite the PCIs EEPROM. Only hope is ACPI, what is correct method to do
>>> define it by ACPI?
>>
>> Define _S3D that will return 2 (for example) and _PRW returning 3 as the
>> deepest sleep state the system may be woken up from.  Then, we'll use
>> D2 (after the @subject patch).
>>
>> The drawback is that the kernel will then think the device can wake up
>> the system.
>
> There also remains a question about runtime power states and resume.
>
> Oleksij, with your patch, which state does the controller get put into
> during runtime suspend, D2 or D3?  (You may need to enable runtime
> suspend by doing
>
> 	echo auto>/sys/bus/pci/devices/0000:00:1d.0/power/control
>
> in order to test this.)  And if the controller is in runtime suspend,
> does it resume correctly when you plug in a new USB device?
>
> I'm pretty sure that without the patch, the controller gets put into D3
> and resume does work.

I do not know if device really suspended, but every thing works like 
before. New usb devices are recognized and working.

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