Merge tag 'ib-mfd-base-acpi-dma-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd into acpi-pm

Pull MFD-related material including ACPI device power management
changes (in addition to MFD, driver core and DMA changes) for v4.3
from Lee Jones.

* tag 'ib-mfd-base-acpi-dma-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd:
  mfd: Add support for Intel Sunrisepoint LPSS devices
  dmaengine: add a driver for Intel integrated DMA 64-bit
  mfd: make mfd_remove_devices() iterate in reverse order
  driver core: implement device_for_each_child_reverse()
  klist: implement klist_prev()
  Driver core: wakeup the parent device before trying probe
  ACPI / PM: Attach ACPI power domain only once
  PM / QoS: Make it possible to expose device latency tolerance to userspace

3 files changed, 40 insertions, 16 deletions

diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
index 717afcd..08dc3ec 100644
--- a/drivers/acpi/device_pm.c
+++ b/drivers/acpi/device_pm.c
@@ -1123,6 +1123,14 @@ int acpi_dev_pm_attach(struct device *dev, bool power_on)
 	if (dev->pm_domain)
 		return -EEXIST;
 
+	/*
+	 * Only attach the power domain to the first device if the
+	 * companion is shared by multiple. This is to prevent doing power
+	 * management twice.
+	 */
+	if (!acpi_device_is_first_physical_node(adev, dev))
+		return -EBUSY;
+
 	acpi_add_pm_notifier(adev, dev, acpi_pm_notify_work_func);
 	dev->pm_domain = &acpi_general_pm_domain;
 	if (power_on) {
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 4683a96..f6aefe9 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -97,6 +97,8 @@ void acpi_device_add_finalize(struct acpi_device *device);
 void acpi_free_pnp_ids(struct acpi_device_pnp *pnp);
 bool acpi_device_is_present(struct acpi_device *adev);
 bool acpi_device_is_battery(struct acpi_device *adev);
+bool acpi_device_is_first_physical_node(struct acpi_device *adev,
+					const struct device *dev);
 
 /* --------------------------------------------------------------------------
                                   Power Resource
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index ec25635..89ff6d2 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -226,6 +226,35 @@ static int create_of_modalias(struct acpi_device *acpi_dev, char *modalias,
 	return len;
 }
 
+/**
+ * acpi_device_is_first_physical_node - Is given dev first physical node
+ * @adev: ACPI companion device
+ * @dev: Physical device to check
+ *
+ * Function checks if given @dev is the first physical devices attached to
+ * the ACPI companion device. This distinction is needed in some cases
+ * where the same companion device is shared between many physical devices.
+ *
+ * Note that the caller have to provide valid @adev pointer.
+ */
+bool acpi_device_is_first_physical_node(struct acpi_device *adev,
+					const struct device *dev)
+{
+	bool ret = false;
+
+	mutex_lock(&adev->physical_node_lock);
+	if (!list_empty(&adev->physical_node_list)) {
+		const struct acpi_device_physical_node *node;
+
+		node = list_first_entry(&adev->physical_node_list,
+					struct acpi_device_physical_node, node);
+		ret = node->dev == dev;
+	}
+	mutex_unlock(&adev->physical_node_lock);
+
+	return ret;
+}
+
 /*
  * acpi_companion_match() - Can we match via ACPI companion device
  * @dev: Device in question
@@ -250,7 +279,6 @@ static int create_of_modalias(struct acpi_device *acpi_dev, char *modalias,
 static struct acpi_device *acpi_companion_match(const struct device *dev)
 {
 	struct acpi_device *adev;
-	struct mutex *physical_node_lock;
 
 	adev = ACPI_COMPANION(dev);
 	if (!adev)
@@ -259,21 +287,7 @@ static struct acpi_device *acpi_companion_match(const struct device *dev)
 	if (list_empty(&adev->pnp.ids))
 		return NULL;
 
-	physical_node_lock = &adev->physical_node_lock;
-	mutex_lock(physical_node_lock);
-	if (list_empty(&adev->physical_node_list)) {
-		adev = NULL;
-	} else {
-		const struct acpi_device_physical_node *node;
-
-		node = list_first_entry(&adev->physical_node_list,
-					struct acpi_device_physical_node, node);
-		if (node->dev != dev)
-			adev = NULL;
-	}
-	mutex_unlock(physical_node_lock);
-
-	return adev;
+	return acpi_device_is_first_physical_node(adev, dev) ? adev : NULL;
 }
 
 static int __acpi_device_uevent_modalias(struct acpi_device *adev,