linux-kernel - Re: 3.12: ethernet controller missing after resuming from suspend to RAM

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Date:	Tue, 11 Feb 2014 12:42:37 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Peter Wu <lekensteyn@...il.com>,
	Bastien Traverse <bastien.traverse@...il.com>,
	linux-kernel@...r.kernel.org, francis.moro@...il.com,
	linux-pm@...r.kernel.org
Subject: Re: 3.12: ethernet controller missing after resuming from suspend to
 RAM

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.

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)


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