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

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Date:	Fri, 1 Jan 2010 19:55:27 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Andreas Mohr <andi@...as.de>
Cc:	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

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).

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.

> Perhaps rename d3_delay to d3_delay__quirk or add something to the
> comment, like "D3->D0 transition time in ms (out-of-spec PCI device quirk)"?
> Or maybe something like
> "custom D3->D0 transition time in ms (for quirky hardware violating the PCI spec's <= 100ms)".
> 
> Thanks for your ongoing great PCI efforts,

You're welcome.

Rafael
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