diff --git a/src/radeon_output.c b/src/radeon_output.c
index 9d9a16c..9acc563 100644
--- a/src/radeon_output.c
+++ b/src/radeon_output.c
@@ -322,6 +322,23 @@ radeon_ddc_connected(xf86OutputPtr output)
 	case CONNECTOR_DVI_D:
 	case CONNECTOR_HDMI_TYPE_A:
 	    if (radeon_output->shared_ddc) {
+		xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR (output->scrn);
+		int i;
+
+		for (i = 0; i < config->num_output; i++) {
+		    if (output != config->output[i]) {
+			RADEONOutputPrivatePtr other_radeon_output =
+			    config->output[i]->driver_private;
+			if (radeon_output->devices & other_radeon_output->devices) {
+			    /* XXX: choose HDMI or DVI based on edid */
+			    if (radeon_output->ConnectorType == CONNECTOR_HDMI_TYPE_A) {
+				ErrorF("HDMI on shared encoder\n");
+				MonType = MT_NONE;
+				break;
+			    }
+			}
+		    }
+		}
 		if (monitor_is_digital(MonInfo))
 		    MonType = MT_DFP;
 		else
@@ -420,6 +437,26 @@ radeon_dpms(xf86OutputPtr output, int mode)
     if ((mode == DPMSModeOn) && radeon_output->enabled)
 	return;
 
+    if (mode != DPMSModeOn) {
+	radeon_encoder_ptr radeon_encoder = radeon_get_encoder(output);
+	xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR (output->scrn);
+	int i;
+
+	for (i = 0; i < config->num_output; i++) {
+	    if (output != config->output[i]) {
+		radeon_encoder_ptr other_radeon_encoder =
+		    radeon_get_encoder(config->output[i]);
+		if (radeon_encoder == other_radeon_encoder) {
+		    xf86CrtcPtr crtc = output->crtc;
+		    if (crtc == NULL)
+			return;
+		    else if (!crtc->enabled)
+			return;
+		}
+	    }
+	}
+    }
+
     if (IS_AVIVO_VARIANT || info->r4xx_atom) {
 	atombios_output_dpms(output, mode);
     } else {