DRM/Radeon: On DVI-I use Load Detection when EDID is bogus.

The Radeon driver uses the analog/digital flag to determine if the
DAC or the TMDS encoder should be enabled on a DVI-I connector.
If the EDID is bogus this flag is no longer reliable. This fix
adds a fallback to DAC load detection to determine if anything
is connected to the DAC. If not and a (bogus) EDID is found it
assumes a digital display is connected.
This works around problems with some crappy IPMI devices using
Radeon ES1000.

Signed-off-by: Egbert Eich <eich@suse.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index 67cfc1795ecd..b884c362a8c2 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -941,7 +941,7 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
         struct drm_mode_object *obj;
         int i;
         enum drm_connector_status ret = connector_status_disconnected;
-        bool dret = false;
+        bool dret = false, broken_edid = false;
 
         if (!force && radeon_check_hpd_status_unchanged(connector))
                 return connector->status;
@@ -965,6 +965,9 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
                                 ret = connector_status_disconnected;
                                 DRM_ERROR("%s: detected RS690 floating bus bug, stopping ddc detect\n", drm_get_connector_name(connector));
                                 radeon_connector->ddc_bus = NULL;
+                        } else {
+                                ret = connector_status_connected;
+                                broken_edid = true; /* defer use_digital to later */
                         }
                 } else {
                         radeon_connector->use_digital = !!(radeon_connector->edid->input & DRM_EDID_INPUT_DIGITAL);
@@ -1047,13 +1050,24 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
 
                         encoder_funcs = encoder->helper_private;
                         if (encoder_funcs->detect) {
-                                if (ret != connector_status_connected) {
-                                        ret = encoder_funcs->detect(encoder, connector);
-                                        if (ret == connector_status_connected) {
-                                                radeon_connector->use_digital = false;
+                                if (!broken_edid) {
+                                        if (ret != connector_status_connected) {
+                                                /* deal with analog monitors without DDC */
+                                                ret = encoder_funcs->detect(encoder, connector);
+                                                if (ret == connector_status_connected) {
+                                                        radeon_connector->use_digital = false;
+                                                }
+                                                if (ret != connector_status_disconnected)
+                                                        radeon_connector->detected_by_load = true;
                                         }
-                                        if (ret != connector_status_disconnected)
-                                                radeon_connector->detected_by_load = true;
+                                } else {
+                                        enum drm_connector_status lret;
+                                        /* assume digital unless load detected otherwise */
+                                        radeon_connector->use_digital = true;
+                                        lret = encoder_funcs->detect(encoder, connector);
+                                        DRM_DEBUG_KMS("load_detect %x returned: %x\n",encoder->encoder_type,lret);
+                                        if (lret == connector_status_connected)
+                                                radeon_connector->use_digital = false;
                                 }
                                 break;
                         }