ethtool: Expand documentation of struct ethtool_test

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 4 deletions

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index e726340d1f8e..f246f3703ed8 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -575,12 +575,25 @@ enum ethtool_test_flags {
         ETH_TEST_FL_EXTERNAL_LB_DONE    = (1 << 3),
 };
 
-/* for requesting NIC test and getting results*/
+/**
+ * struct ethtool_test - device self-test invocation
+ * @cmd: Command number = %ETHTOOL_TEST
+ * @flags: A bitmask of flags from &enum ethtool_test_flags.  Some
+ *      flags may be set by the user on entry; others may be set by
+ *      the driver on return.
+ * @len: On return, the number of test results
+ * @data: Array of test results
+ *
+ * Users must use %ETHTOOL_GSSET_INFO or %ETHTOOL_GDRVINFO to find the
+ * number of test results that will be returned.  They must allocate a
+ * buffer of the appropriate size (8 * number of results) immediately
+ * following this structure.
+ */
 struct ethtool_test {
-        __u32   cmd;            /* ETHTOOL_TEST */
-        __u32   flags;          /* ETH_TEST_FL_xxx */
+        __u32   cmd;
+        __u32   flags;
         __u32   reserved;
-        __u32   len;            /* result length, in number of u64 elements */
+        __u32   len;
         __u64   data[0];
 };