2 files changed, 49 insertions, 15 deletions

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 37fdf820acf1..2c8771305aca 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -49,6 +49,22 @@ int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
 }
 EXPORT_SYMBOL(fw_csr_iterator_next);
 
+static const u32 *search_directory(const u32 *directory, int search_key)
+{
+	struct fw_csr_iterator ci;
+	int key, value;
+
+	search_key |= CSR_DIRECTORY;
+
+	fw_csr_iterator_init(&ci, directory);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		if (key == search_key)
+			return ci.p - 1 + value;
+	}
+
+	return NULL;
+}
+
 static const u32 *search_leaf(const u32 *directory, int search_key)
 {
 	struct fw_csr_iterator ci;
@@ -253,27 +269,44 @@ static ssize_t show_immediate(struct device *dev,
 	struct config_rom_attribute *attr =
 		container_of(dattr, struct config_rom_attribute, attr);
 	struct fw_csr_iterator ci;
-	const u32 *dir;
-	int key, value, ret = -ENOENT;
+	const u32 *directories[] = {NULL, NULL};
+	int i, value = -1;
 
 	down_read(&fw_device_rwsem);
 
-	if (is_fw_unit(dev))
-		dir = fw_unit(dev)->directory;
-	else
-		dir = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
+	if (is_fw_unit(dev)) {
+		directories[0] = fw_unit(dev)->directory;
+	} else {
+		const u32 *root_directory = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
+		const u32 *vendor_directory = search_directory(root_directory, CSR_VENDOR);
 
-	fw_csr_iterator_init(&ci, dir);
-	while (fw_csr_iterator_next(&ci, &key, &value))
-		if (attr->key == key) {
-			ret = snprintf(buf, buf ? PAGE_SIZE : 0,
-				       "0x%06x\n", value);
-			break;
+		if (!vendor_directory) {
+			directories[0] = root_directory;
+		} else {
+			// Legacy layout of configuration ROM described in Annex 1 of
+			// 'Configuration ROM for AV/C Devices 1.0 (December 12, 2000, 1394 Trading
+			// Association, TA Document 1999027)'.
+			directories[0] = vendor_directory;
+			directories[1] = root_directory;
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) {
+		int key, val;
+
+		fw_csr_iterator_init(&ci, directories[i]);
+		while (fw_csr_iterator_next(&ci, &key, &val)) {
+			if (attr->key == key)
+				value = val;
 		}
+	}
 
 	up_read(&fw_device_rwsem);
 
-	return ret;
+	if (value < 0)
+		return -ENOENT;
+
+	return snprintf(buf, buf ? PAGE_SIZE : 0, "0x%06x\n", value);
 }
 
 #define IMMEDIATE_ATTR(name, key)				\
diff --git a/drivers/firewire/device-attribute-test.c b/drivers/firewire/device-attribute-test.c
index 495af65c33b5..689115433425 100644
--- a/drivers/firewire/device-attribute-test.c
+++ b/drivers/firewire/device-attribute-test.c
@@ -199,8 +199,9 @@ static void device_attr_legacy_avc(struct kunit *test)
 	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[0].attr, buf), 0);
 	KUNIT_EXPECT_STREQ(test, buf, "0x012345\n");
 
-	// Model immediate entry is not found.
-	KUNIT_EXPECT_LT(test, show_immediate(node_dev, &config_rom_attributes[4].attr, buf), 0);
+	// Model immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[4].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0xfedcba\n");
 
 	// Descriptor leaf entry for vendor is not found.
 	KUNIT_EXPECT_LT(test, show_text_leaf(node_dev, &config_rom_attributes[5].attr, buf), 0);