1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index f899afd924b4..eaacfd0920df 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -1628,6 +1628,32 @@ intel_sdvo_hdmi_sink_detect(struct drm_connector *connector, u16 response)
         edid = drm_get_edid(&intel_output->base,
                             intel_output->ddc_bus);
 
+        /* This is only applied to SDVO cards with multiple outputs */
+        if (edid == NULL && intel_sdvo_multifunc_encoder(intel_output)) {
+                uint8_t saved_ddc, temp_ddc;
+                saved_ddc = sdvo_priv->ddc_bus;
+                temp_ddc = sdvo_priv->ddc_bus >> 1;
+                /*
+                 * Don't use the 1 as the argument of DDC bus switch to get
+                 * the EDID. It is used for SDVO SPD ROM.
+                 */
+                while(temp_ddc > 1) {
+                        sdvo_priv->ddc_bus = temp_ddc;
+                        edid = drm_get_edid(&intel_output->base,
+                                intel_output->ddc_bus);
+                        if (edid) {
+                                /*
+                                 * When we can get the EDID, maybe it is the
+                                 * correct DDC bus. Update it.
+                                 */
+                                sdvo_priv->ddc_bus = temp_ddc;
+                                break;
+                        }
+                        temp_ddc >>= 1;
+                }
+                if (edid == NULL)
+                        sdvo_priv->ddc_bus = saved_ddc;
+        }
         /* when there is no edid and no monitor is connected with VGA
          * port, try to use the CRT ddc to read the EDID for DVI-connector
          */