[PATCH] EDD: Check for correct EDD 3.0 length

[Hannes Reinecke <hare@suse.de>]

There are two competing EDD 3.0 specifications,
the original one from Phoenix
<http://mbldr.sourceforge.net/specsedd30.pdf>
and the T-13 approved one
<http://www.t13.org/documents/UploadedDocuments/docs2004/d1572r3-EDD3.pdf>

They differ in the length of the device_path field, which
is one quad word for the Phoenix spec and two quad words
for the T-13 spec. So we need to test for both lengths
and blank out the second quad word when a Phoenix
version is detected.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>

diff --git a/drivers/firmware/edd.c b/drivers/firmware/edd.c
index e229576..beedf4c 100644
--- a/drivers/firmware/edd.c
+++ b/drivers/firmware/edd.c
@@ -192,6 +192,13 @@ edd_show_interface(struct edd_device *edev, char *buf)
 			p += scnprintf(p, left, " ");
 		}
 	}
+	/*
+	 * Phoenix EDD 3.0 reserves only one quad word for the
+	 * device path, so blank out the second quad word.
+	 */
+	if (info->params.device_path_info_length == 36)
+		info->params.device_path.unknown.reserved2 = 0;
+
 	if (!strncmp(info->params.interface_type, "ATAPI", 5)) {
 		p += scnprintf(p, left, "\tdevice: %u  lun: %u\n",
 			     info->params.device_path.atapi.device,
@@ -545,8 +552,12 @@ edd_has_edd30(struct edd_device *edev)
 	}
 
 
-	/* We support only T13 spec */
-	if (info->params.device_path_info_length != 44)
+	/*
+	 * Phoenix EDD 3.0 specifies this to be 36,
+	 * T-13 EDD 3.0 uses 44. So check for both.
+	 */
+	if (info->params.device_path_info_length != 36 &&
+	    info->params.device_path_info_length != 44)
 		return 0;
 
 	for (i = 30; i < info->params.device_path_info_length + 30; i++)