diff --git a/compositor/main.c b/compositor/main.c
index 1d8d86d3f..af6ec272b 100644
--- a/compositor/main.c
+++ b/compositor/main.c
@@ -708,7 +708,8 @@ usage(int error_code)
 	fprintf(out,
 		"Options for drm:\n\n"
 		"  --seat=SEAT\t\tThe seat that weston should run on, instead of the seat defined in XDG_SEAT\n"
-		"  --drm-device=CARD\tThe DRM device to use, e.g. \"card0\".\n"
+		"  --drm-device=CARD\tThe DRM device to use for rendering and output, e.g. \"card0\".\n"
+		"  --additional-devices=CARD\tSecondary DRM devices to use for output only, e.g. \"card1,card2\".\n"
 		"  --use-pixman\t\tUse the pixman (CPU) renderer (deprecated alias for --renderer=pixman)\n"
 		"  --current-mode\tPrefer current KMS mode over EDID preferred mode\n"
 		"  --continue-without-input\tAllow the compositor to start without input devices\n\n");
diff --git a/man/weston-drm.man b/man/weston-drm.man
index 3cfd371de..fca47fd68 100644
--- a/man/weston-drm.man
+++ b/man/weston-drm.man
@@ -219,10 +219,16 @@ switching to the monitor preferred mode.
 \fB\-\-drm\-device\fR=\fIcardN\fR
 Use the DRM device
 .I cardN
-instead of the default heuristics based on seat assignments and boot VGA
+for rendering and output instead of the default heuristics based on seat assignments and boot VGA
 status. For example, use
 .BR card0 .
 .TP
+\fB\-\-additional\-devices\fR=\fIcardN\fR
+Comma separated list of secondary DRM devices
+.I cardM,cardN
+that will only be used as outputs, but not for rendering. For example, use
+.BR card1,card2 .
+.TP
 \fB\-\-seat\fR=\fIseatid\fR
 Use graphics and input devices designated for seat
 .I seatid