linux-kernel - Re: [PATCH 2/3] Adapt the sky2 driver to the reworked PCI PM

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Date:	Fri, 15 Aug 2008 15:01:57 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	netdev@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
	Jeff Garzik <jeff@...zik.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	Stephen Hemminger <stephen.hemminger@...tta.com>
Subject: Re: [PATCH 2/3] Adapt the sky2 driver to the reworked PCI PM

On Friday, 15 of August 2008, Stephen Hemminger wrote:
> On Thu, 14 Aug 2008 23:38:17 +0200
> "Rafael J. Wysocki" <rjw@...k.pl> wrote:
> 
> > Adapt the sky2 driver to the reworked PCI PM
> > 
> > * Use device_set_wakeup_enable() and friends as needed
> > * Remove an open-coded reference to the standard PCI PM registers
> > * Use pci_prepare_to_sleep() and pci_back_from_sleep() in the
> >   ->suspend() and ->resume() callbacks
> > * Use the observation that it is sufficient to call pci_enable_wake()
> >   once, unless it fails
> > 
> > Tested on Asus M3A32-MVP (Yukon-2 EC Ultra rev 3).
> > 
> > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> > ---
> >  drivers/net/sky2.c |   34 ++++++++++------------------------
> >  1 file changed, 10 insertions(+), 24 deletions(-)
> > 
> > Index: linux-2.6/drivers/net/sky2.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/net/sky2.c
> > +++ linux-2.6/drivers/net/sky2.c
> > @@ -3035,7 +3035,8 @@ static int sky2_set_wol(struct net_devic
> >  	struct sky2_port *sky2 = netdev_priv(dev);
> >  	struct sky2_hw *hw = sky2->hw;
> >  
> > -	if (wol->wolopts & ~sky2_wol_supported(sky2->hw))
> > +	if ((wol->wolopts & ~sky2_wol_supported(sky2->hw))
> > +	    || !device_can_wakeup(&hw->pdev->dev))
> >  		return -EOPNOTSUPP;
> >  
> 
> There was a regression in earlier releases caused because some BIOS's
> are wrong, and device can wakeup.

device_can_wakeup() returns 'true' if the device is capable of generating PME#
from at least one low power state (this is determined on the basis of the
contents of the device's PCI PM registers - please have a look at
drivers/pci/pci_pm_init() for details) or if ACPI tells us it can wake up.
IOW, the BIOSes opinion doesn't matter if we find that the device is capable of
generating PME#, so the regression must have been related to something else.
I'm very interested in the details, if available.

Of course, since we rely on the ability of the device to generate PME# and
device_can_wakeup() returning 'false' means that the device cannot generate
PME# from any state, it's reasonable to check it IMO.

Thanks,
Rafael
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