From f86e8c91d020d05c584d53d7033fe6d05a16aef1 Mon Sep 17 00:00:00 2001
From: Mark Thompson <sw@jkqxz.net>
Date: Wed, 21 Mar 2018 21:13:16 +0000
Subject: [PATCH] hwcontext_drm: Clarify value for unknown format modifiers

---
 libavutil/hwcontext_drm.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavutil/hwcontext_drm.h b/libavutil/hwcontext_drm.h
index 2e225451e1..42709f215e 100644
--- a/libavutil/hwcontext_drm.h
+++ b/libavutil/hwcontext_drm.h
@@ -58,6 +58,9 @@ typedef struct AVDRMObjectDescriptor {
     size_t size;
     /**
      * Format modifier applied to the object (DRM_FORMAT_MOD_*).
+     *
+     * If the format modifier is unknown then this should be set to
+     * DRM_FORMAT_MOD_INVALID.
      */
     uint64_t format_modifier;
 } AVDRMObjectDescriptor;