linux-kernel - Re: [PATCH] PCI / PM: Use per-device D3 delays

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Date:	Fri, 1 Jan 2010 21:12:35 +0100
From:	Andreas Mohr <andi@...as.de>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Andreas Mohr <andi@...as.de>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Stephen Hemminger <shemminger@...ux-foundation.org>,
	"Maciej J. Woloszyk" <mat@....com.pl>
Subject: Re: [PATCH] PCI / PM: Use per-device D3 delays

Hi,

On Fri, Jan 01, 2010 at 07:55:27PM +0100, Rafael J. Wysocki wrote:
> On Friday 01 January 2010, Andreas Mohr wrote:
> > Hi,
> > 
> > While the bug report mentions "So it's just quirky hardware.",
> > the implementation of your patch makes it seem like this delay attribute is
> > totally "norm"al behaviour - I'm missing some more aggressive wording.
> 
> That's because it works both ways (please look at the changelog).

Ah, ok.

> I know of a few devices that don't need the PCI-prescribed 10 ms wait when
> going from D3 to D0 and their drivers may use the d3_delay field to actually
> set a _shorter_ delay.

Then why is the value lower-bounded by pci_pm_d3_delay
(which, puzzlingly, was initialized to PCI_PM_D3_WAIT and thus 10
before, which the patch now removes!), in pci_dev_d3_sleep()?
(and pci_pm_d3_delay is being quirked in drivers/pci/quirks.c only,
to 120)

Confused,

Andreas Mohr
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