linux-kernel - Re: [PATCH] ACPI / platform / LPSS: disable async suspend/resume of LPSS devices

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Date:	Tue, 23 Sep 2014 01:17:08 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	"Fu, Zhonghui" <zhonghui.fu@...ux.intel.com>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>, lenb@...nel.org,
	linux-acpi@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / platform / LPSS: disable async suspend/resume of LPSS devices

On Monday, September 22, 2014 10:45:42 PM Fu, Zhonghui wrote:
> 

[cut]

> >>>
> >>> This operation is reading data from Operation Region of one operand object in name space. I don't know the reason of hang at this point. Could you please give out some explanation about this?
> >> I don't know the exact reason why this particular read hangs, but this means
> >> that, perhaps, instead of disabling async suspend/resume for all LPSS devices
> >> altogether, perhaps we can serialize their acpi_dev_resume_early()?
> >>
> >> Rafael
> > Do you mean keeping other phases(prepare, suspend, suspend_late, suspend_noirq, resume_noirq, resume, complete) of suspend/resume asynchronous, and only serializing "resume_early" phase for all LPSS devices?
> >
> > Thanks,
> > Zhonghui
> Hi, Rafael
> 
> Could you please confirm my understanding?

This is not what I meant.

Since we have a PM domain for the LPSS devices already, why don't we add an
internal lock to that PM domain and acquire it over executing either
acpi_dev_suspend_late() (during suspend) or acpi_dev_resume_early() (during
resume) for all of them?

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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