linux-kernel - Re: [PATCH] SATA / AHCI: Do not play with the link PM during suspend to RAM

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Date:	Tue, 17 Aug 2010 14:10:20 +0200
From:	Stephan Diestelhorst <stephan.diestelhorst@....com>
To:	Tejun Heo <htejun@...il.com>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
	"linux-pm@...ts.osdl.org" <linux-pm@...ts.osdl.org>,
	Stephan Diestelhorst <stephan.diestelhorst@...il.com>
Subject: Re: [PATCH] SATA / AHCI: Do not play with the link PM during suspend to RAM

Hi,

On Tuesday 17 August 2010, 13:29:05 Tejun Heo wrote:
> Hello,
> 
> On 08/17/2010 01:19 PM, Rafael J. Wysocki wrote:
> > Well, I wonder what the real reason for doing the link power management
> > thing at this particular point in the suspend code path is.  It just seems to
> > disable the link power management, but then the controller is put into a
> > low-power state and is reset from scratch during resume, so I'm not quite
> > sure how skipping that code could possibly lead to any problems.
> 
> > Perhaps we could move the link PM manipulation to the prepare stage
> > of suspend?
> 
> Yeah, one possibility is that the devices misbehave if they receive
> LPM commands while suspended.  Does commenting out sd_suspend resolve
> the issue too?

If you want me to test anything... let me know. Since I do not know
much about the ATA code, I do not know what to change where. (A simple
grep for sd_suspend in drivers/ata didn't turn up anything.)

Thanks,
  Stephan
-- 
Stephan Diestelhorst, AMD Operating System Research Center
stephan.diestelhorst@....com, Tel. +49 (0)351 448 356 719

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
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