From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Mika Westerberg <mika.westerberg@linux.intel.com>,
        Peter Wu <lekensteyn@gmail.com>
Cc: Bastien Traverse <bastien.traverse@gmail.com>,
        linux-kernel@vger.kernel.org, francis.moro@gmail.com,
        linux-pm@vger.kernel.org
Subject: Re: 3.12: ethernet controller missing after resuming from suspend to RAM
Date: Tue, 11 Feb 2014 13:57:22 +0100
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On Tuesday, February 11, 2014 12:42:37 PM Mika Westerberg wrote:
> On Mon, Feb 10, 2014 at 11:39:29PM +0100, Rafael J. Wysocki wrote:
> > > _STA() returns 0x0A instead of 0x0F. Could there be something missing in
> > > the ACPI hotplug code that overlooks this and removes the device on resume?
> > 
> > That is possible.  Actually even quite likely, but let's wait for the response
> > from Peter.
> 
> Here's a hack that should take the 0xa return value into consideration. It
> turned out that this case is even mentioned in the ACPI spec.

Looks reasonable.

Peter, please check if this one makes a difference for you.

> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index e2a783fdb98f..014381b42d86 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -730,6 +730,17 @@ static unsigned int get_slot_status(struct acpiphp_slot *slot)
>  	return (unsigned int)sta;
>  }
>  
> +static inline bool device_sta_valid(unsigned long long sta)
> +{
> +	/*
> +	 * ACPI spec says that _STA may return bit 0 clear with bit 8 set
> +	 * if the device is valid but does not require device driver to be
> +	 * loaded (chapter 6.3.7).
> +	 */
> +	unsigned mask = ACPI_STA_DEVICE_ENABLED | ACPI_STA_DEVICE_FUNCTIONING;
> +	return (sta & mask) == mask;
> +}
> +
>  /**
>   * trim_stale_devices - remove PCI devices that are not responding.
>   * @dev: PCI device to start walking the hierarchy from.
> @@ -745,7 +756,7 @@ static void trim_stale_devices(struct pci_dev *dev)
>  		unsigned long long sta;
>  
>  		status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
> -		alive = (ACPI_SUCCESS(status) && sta == ACPI_STA_ALL)
> +		alive = (ACPI_SUCCESS(status) && device_sta_valid(sta))
>  			|| acpiphp_no_hotplug(handle);
>  	}
>  	if (!alive) {
> @@ -792,7 +803,7 @@ static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
>  		mutex_lock(&slot->crit_sect);
>  		if (slot_no_hotplug(slot)) {
>  			; /* do nothing */
> -		} else if (get_slot_status(slot) == ACPI_STA_ALL) {
> +		} else if (device_sta_valid(get_slot_status(slot))) {
>  			/* remove stale devices if any */
>  			list_for_each_entry_safe_reverse(dev, tmp,
>  							 &bus->devices, bus_list)
> 
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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