linux-kernel - Re: [PATCH] e100: do not go D3 in shutdown unless system is powering off

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Message-ID: <20090421215248.GF6147@vespa.holoscopio.com>
Date:	Tue, 21 Apr 2009 18:52:48 -0300
From:	Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	auke-jan.h.kok@...el.com, e1000-devel@...ts.sourceforge.net
Subject: Re: [PATCH] e100: do not go D3 in shutdown unless system is
	powering off

On Mon, Apr 20, 2009 at 09:13:59PM +0200, Rafael J. Wysocki wrote:
> On Monday 20 April 2009, Thadeu Lima de Souza Cascardo wrote:
> > After experimenting with kexec with the last merges after 2.6.29, I've
> > had some problems when probing e100. It would not read the eeprom. After
> > some bisects, I realized this has been like that since forever (at least
> > 2.6.18). The problem is that shutdown is doing the same thing that
> > suspend does and puts the device in D3 state. I couldn't find a way to
> > get the device back to a sane state in the probe function. So, based on
> > some similar patches from Rafael J. Wysocki for e1000, e1000e and ixgbe,
> > I wrote this one for e100.
> > 
> > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com>
> > ---
> >  drivers/net/e100.c |   27 +++++++++++++++++++++------
> >  1 files changed, 21 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/net/e100.c b/drivers/net/e100.c
> > index c0f8443..3db7b29 100644
> > --- a/drivers/net/e100.c
> > +++ b/drivers/net/e100.c
> > @@ -2728,7 +2728,7 @@ static void __devexit e100_remove(struct pci_dev *pdev)
> >  #define E100_82552_SMARTSPEED   0x14   /* SmartSpeed Ctrl register */
> >  #define E100_82552_REV_ANEG     0x0200 /* Reverse auto-negotiation */
> >  #define E100_82552_ANEG_NOW     0x0400 /* Auto-negotiate now */
> > -static int e100_suspend(struct pci_dev *pdev, pm_message_t state)
> > +static int __e100_shutdown(struct pci_dev *pdev, bool *enable_wake)
> >  {
> >  	struct net_device *netdev = pci_get_drvdata(pdev);
> >  	struct nic *nic = netdev_priv(netdev);
> > @@ -2749,19 +2749,31 @@ static int e100_suspend(struct pci_dev *pdev, pm_message_t state)
> >  			           E100_82552_SMARTSPEED, smartspeed |
> >  			           E100_82552_REV_ANEG | E100_82552_ANEG_NOW);
> >  		}
> > -		if (pci_enable_wake(pdev, PCI_D3cold, true))
> > -			pci_enable_wake(pdev, PCI_D3hot, true);
> > +		*enable_wake = true;
> >  	} else {
> > -		pci_enable_wake(pdev, PCI_D3hot, false);
> > +		*enable_wake = false;
> >  	}
> >  
> >  	pci_disable_device(pdev);
> > -	pci_set_power_state(pdev, PCI_D3hot);
> >  
> >  	return 0;
> >  }
> >  
> > +static void __e100_power_off(struct pci_dev *pdev, bool wake)
> > +{
> > +	pci_enable_wake(pdev, PCI_D3hot, wake);
> > +	pci_set_power_state(pdev, PCI_D3hot);
> > +}
> > +
> >  #ifdef CONFIG_PM
> > +static int e100_suspend(struct pci_dev *pdev, pm_message_t state)
> > +{
> > +	bool wake;
> > +	int retval = __e100_shutdown(pdev, &wake);
> 
> I'd call pci_prepare_to_sleep() here if wake is 'true' instead of the
> __e100_power_off(), because there is a chance the platform will prefer some
> other power state to put the device into.
> 
> In fact, looking at the entire driver's code, I think you could just call
> pci_prepare_to_sleep(pdev) here instead of __e100_power_off(pdev, wake)
> and discard the value of wake.
> 

If there is no advantage in using pci_enable_wake with false in the case
the device cannot WOL or ASF, I will just use pci_prepare_to_sleep and
drop this enable_wake/wake variable in both suspend and shutdown. Any
reason we should use pci_enable_wake with false?

> > +	__e100_power_off(pdev, wake);
> 
> Also, retval will always be 0 as far as I can see and if it could be different
> from 0, it would be a good idea to return the error code before putting the
> device into a low power state (.resume() won't be called for this device if
> .suspend() fails).
> 
> Apart from this, the patch looks fine to me.
> 
> > +	return retval;
> > +}
> > +
> >  static int e100_resume(struct pci_dev *pdev)
> >  {
> >  	struct net_device *netdev = pci_get_drvdata(pdev);
> > @@ -2792,7 +2804,10 @@ static int e100_resume(struct pci_dev *pdev)
> >  
> >  static void e100_shutdown(struct pci_dev *pdev)
> >  {
> > -	e100_suspend(pdev, PMSG_SUSPEND);
> > +	bool wake;
> > +	__e100_shutdown(pdev, &wake);
> > +	if (system_state == SYSTEM_POWER_OFF)
> > +		__e100_power_off(pdev, wake);
> >  }
> >  
> >  /* ------------------ PCI Error Recovery infrastructure  -------------- */
> 
> Best,
> Rafael

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