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

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Date:	Mon, 20 Apr 2009 21:13:59 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com>
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 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.

> +	__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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