drm/nouveau: Try to fetch an EDID from OF if DDC fails.

More Apple brain damage, it fixes the modesetting failure on an eMac
G4 (fdo bug 29810).

Reported-by: Zoltan Varnagy <doi@freemail.hu>
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 87186a4bbf03..98c214c34922 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -130,6 +130,36 @@ nouveau_connector_ddc_detect(struct drm_connector *connector,
         return NULL;
 }
 
+static struct nouveau_encoder *
+nouveau_connector_of_detect(struct drm_connector *connector)
+{
+#ifdef __powerpc__
+        struct drm_device *dev = connector->dev;
+        struct nouveau_connector *nv_connector = nouveau_connector(connector);
+        struct nouveau_encoder *nv_encoder;
+        struct device_node *cn, *dn = pci_device_to_OF_node(dev->pdev);
+
+        if (!dn ||
+            !((nv_encoder = find_encoder_by_type(connector, OUTPUT_TMDS)) ||
+              (nv_encoder = find_encoder_by_type(connector, OUTPUT_ANALOG))))
+                return NULL;
+
+        for_each_child_of_node(dn, cn) {
+                const char *name = of_get_property(cn, "name", NULL);
+                const void *edid = of_get_property(cn, "EDID", NULL);
+                int idx = name ? name[strlen(name) - 1] - 'A' : 0;
+
+                if (nv_encoder->dcb->i2c_index == idx && edid) {
+                        nv_connector->edid =
+                                kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
+                        of_node_put(cn);
+                        return nv_encoder;
+                }
+        }
+#endif
+        return NULL;
+}
+
 static void
 nouveau_connector_set_encoder(struct drm_connector *connector,
                               struct nouveau_encoder *nv_encoder)
@@ -225,6 +255,12 @@ nouveau_connector_detect(struct drm_connector *connector, bool force)
                 return connector_status_connected;
         }
 
+        nv_encoder = nouveau_connector_of_detect(connector);
+        if (nv_encoder) {
+                nouveau_connector_set_encoder(connector, nv_encoder);
+                return connector_status_connected;
+        }
+
 detect_analog:
         nv_encoder = find_encoder_by_type(connector, OUTPUT_ANALOG);
         if (!nv_encoder && !nouveau_tv_disable)