diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index ec25635..a12e522 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2188,6 +2188,22 @@ static void acpi_init_coherency(struct acpi_device *adev)
 	acpi_status status;
 	struct acpi_device *parent = adev->parent;
 
+	/**
+	 * Currently, we only support _CCA=1 (i.e. coherent_dma=1)
+	 * This should be equivalent to specifying dma-coherent for
+	 * a device in OF.
+	 *
+	 * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1),
+	 * we have two choices:
+	 * case 1. Do not support and disable DMA.
+	 * case 2. Support but rely on arch-specific cache maintenance for
+	 *         non-coherent DMA operations.
+	 * Currently, we implement case 1 above.
+	 *
+	 * For the case when _CCA is missing (i.e. cca_seen=0) and
+	 * platform specifies ACPI_CCA_REQUIRED, we do not support DMA,
+	 * and fallback to arch-specific default handling.
+	 */
 	if (parent && parent->flags.cca_seen) {
 		/*
 		 * From ACPI spec, OSPM will ignore _CCA if an ancestor
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 83061ca..718942b 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -389,24 +389,6 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent)
 	if (!adev)
 		return ret;
 
-	/**
-	 * Currently, we only support _CCA=1 (i.e. coherent_dma=1)
-	 * This should be equivalent to specifyig dma-coherent for
-	 * a device in OF.
-	 *
-	 * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1),
-	 * There are two cases:
-	 * case 1. Do not support and disable DMA.
-	 * case 2. Support but rely on arch-specific cache maintenance for
-	 *         non-coherence DMA operations.
-	 * Currently, we implement case 1 above.
-	 *
-	 * For the case when _CCA is missing (i.e. cca_seen=0) and
-	 * platform specifies ACPI_CCA_REQUIRED, we do not support DMA,
-	 * and fallback to arch-specific default handling.
-	 *
-	 * See acpi_init_coherency() for more info.
-	 */
 	if (adev->flags.coherent_dma) {
 		ret = true;
 		if (coherent)

commit 84cfb2213cd400fef227ec0d7829ec4e12895da9
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Thu Aug 13 19:49:52 2015 -0500

    ACPI / scan: Rename acpi_check_dma() to acpi_dma_is_coherent()
    
    The name "acpi_check_dma()" doesn't give any much indication about what
    exactly it checks.  The function also returns information both as a normal
    return value and as the "bool *coherent" return parameter.  But "*coherent"
    doesn't actually give any extra information: it is unchanged when returning
    false and set to true when returning true.
    
    Rename acpi_check_dma() to acpi_dma_is_coherent() so the callers read more
    naturally.  Drop the return parameter and just use the function return
    value.
    
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
index 06a67d5..fc6138d 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -103,7 +103,7 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev)
 	pdevinfo.res = resources;
 	pdevinfo.num_res = count;
 	pdevinfo.fwnode = acpi_fwnode_handle(adev);
-	pdevinfo.dma_mask = acpi_check_dma(adev, NULL) ? DMA_BIT_MASK(32) : 0;
+	pdevinfo.dma_mask = acpi_dma_is_coherent(adev) ? DMA_BIT_MASK(32) : 0;
 	pdev = platform_device_register_full(&pdevinfo);
 	if (IS_ERR(pdev))
 		dev_err(&adev->dev, "platform device creation failed: %ld\n",
diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index b9657af..89b1cf8 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -168,7 +168,6 @@ int acpi_bind_one(struct device *dev, struct acpi_device *acpi_dev)
 	struct list_head *physnode_list;
 	unsigned int node_id;
 	int retval = -EINVAL;
-	bool coherent;
 
 	if (has_acpi_companion(dev)) {
 		if (acpi_dev) {
@@ -225,8 +224,8 @@ int acpi_bind_one(struct device *dev, struct acpi_device *acpi_dev)
 	if (!has_acpi_companion(dev))
 		ACPI_COMPANION_SET(dev, acpi_dev);
 
-	if (acpi_check_dma(acpi_dev, &coherent))
-		arch_setup_dma_ops(dev, 0, 0, NULL, coherent);
+	if (acpi_dma_is_coherent(acpi_dev))
+		arch_setup_dma_ops(dev, 0, 0, NULL, true);
 
 	acpi_physnode_link_name(physical_node_name, node_id);
 	retval = sysfs_create_link(&acpi_dev->dev.kobj, &dev->kobj,
diff --git a/drivers/base/property.c b/drivers/base/property.c
index f3f6d16..1124130 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -523,13 +523,9 @@ EXPORT_SYMBOL_GPL(device_get_child_node_count);
 
 bool device_dma_is_coherent(struct device *dev)
 {
-	bool coherent = false;
-
 	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
-		coherent = of_dma_is_coherent(dev->of_node);
-	else
-		acpi_check_dma(ACPI_COMPANION(dev), &coherent);
+		return of_dma_is_coherent(dev->of_node);
 
-	return coherent;
+	return acpi_dma_is_coherent(ACPI_COMPANION(dev));
 }
 EXPORT_SYMBOL_GPL(device_dma_is_coherent);
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 718942b..39f1be6 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -382,19 +382,12 @@ struct acpi_device {
 	void (*remove)(struct acpi_device *);
 };
 
-static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent)
+static inline bool acpi_dma_is_coherent(struct acpi_device *adev)
 {
-	bool ret = false;
+	if (adev && adev->flags.coherent_dma)
+		return true;
 
-	if (!adev)
-		return ret;
-
-	if (adev->flags.coherent_dma) {
-		ret = true;
-		if (coherent)
-			*coherent = adev->flags.coherent_dma;
-	}
-	return ret;
+	return false;
 }
 
 static inline bool is_acpi_node(struct fwnode_handle *fwnode)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d2445fa..f29b8b5 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -562,7 +562,7 @@ static inline int acpi_device_modalias(struct device *dev,
 	return -ENODEV;
 }
 
-static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent)
+static inline bool acpi_dma_is_coherent(struct acpi_device *adev)
 {
 	return false;
 }
