1 files changed, 19 insertions, 2 deletions

diff --git a/drivers/gpu/drm/nouveau/nv04_dac.c b/drivers/gpu/drm/nouveau/nv04_dac.c
index bcc8090adb2..2d0fee5f09c 100644
--- a/drivers/gpu/drm/nouveau/nv04_dac.c
+++ b/drivers/gpu/drm/nouveau/nv04_dac.c
@@ -314,9 +314,12 @@ nv17_dac_detect(struct drm_encoder *encoder, struct drm_connector *connector)
 {
         struct drm_device *dev = encoder->dev;
         struct dcb_entry *dcb = nouveau_encoder(encoder)->dcb;
-        uint32_t sample = nv17_dac_sample_load(encoder);
 
-        if (sample & NV_PRAMDAC_TEST_CONTROL_SENSEB_ALLHI) {
+        if (nv04_dac_in_use(encoder))
+                return connector_status_disconnected;
+
+        if (nv17_dac_sample_load(encoder) &
+            NV_PRAMDAC_TEST_CONTROL_SENSEB_ALLHI) {
                 NV_INFO(dev, "Load detected on output %c\n",
                         '@' + ffs(dcb->or));
                 return connector_status_connected;
@@ -329,6 +332,9 @@ static bool nv04_dac_mode_fixup(struct drm_encoder *encoder,
                                 struct drm_display_mode *mode,
                                 struct drm_display_mode *adjusted_mode)
 {
+        if (nv04_dac_in_use(encoder))
+                return false;
+
         return true;
 }
 
@@ -427,6 +433,17 @@ void nv04_dac_update_dacclk(struct drm_encoder *encoder, bool enable)
         }
 }
 
+/* Check if the DAC corresponding to 'encoder' is being used by
+ * someone else. */
+bool nv04_dac_in_use(struct drm_encoder *encoder)
+{
+        struct drm_nouveau_private *dev_priv = encoder->dev->dev_private;
+        struct dcb_entry *dcb = nouveau_encoder(encoder)->dcb;
+
+        return nv_gf4_disp_arch(encoder->dev) &&
+                (dev_priv->dac_users[ffs(dcb->or) - 1] & ~(1 << dcb->index));
+}
+
 static void nv04_dac_dpms(struct drm_encoder *encoder, int mode)
 {
         struct drm_device *dev = encoder->dev;