3 files changed, 24 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 3618d29c79a2..09292193dafe 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -258,6 +258,17 @@ drm_do_probe_ddc_edid(struct i2c_adapter *adapter, unsigned char *buf,
         return ret == 2 ? 0 : -1;
 }
 
+static bool drm_edid_is_zero(u8 *in_edid, int length)
+{
+        int i;
+        u32 *raw_edid = (u32 *)in_edid;
+
+        for (i = 0; i < length / 4; i++)
+                if (*(raw_edid + i) != 0)
+                        return false;
+        return true;
+}
+
 static u8 *
 drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
 {
@@ -273,6 +284,10 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
                         goto out;
                 if (drm_edid_block_valid(block))
                         break;
+                if (i == 0 && drm_edid_is_zero(block, EDID_LENGTH)) {
+                        connector->null_edid_counter++;
+                        goto carp;
+                }
         }
         if (i == 4)
                 goto carp;
diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index 9c2929c7e79f..c04e18ee8a87 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -836,6 +836,13 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
                 if (!radeon_connector->edid) {
                         DRM_ERROR("%s: probed a monitor but no|invalid EDID\n",
                                         drm_get_connector_name(connector));
+                        /* rs690 seems to have a problem with connectors not existing and always
+                         * return a block of 0's. If we see this just stop polling on this output */
+                        if ((rdev->family == CHIP_RS690 || rdev->family == CHIP_RS740) && radeon_connector->base.null_edid_counter) {
+                                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 {
                         radeon_connector->use_digital = !!(radeon_connector->edid->input & DRM_EDID_INPUT_DIGITAL);
 
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 9573e0ce3120..33d12f87f0e0 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -520,6 +520,8 @@ struct drm_connector {
         uint32_t encoder_ids[DRM_CONNECTOR_MAX_ENCODER];
         uint32_t force_encoder_id;
         struct drm_encoder *encoder; /* currently active encoder */
+
+        int null_edid_counter; /* needed to workaround some HW bugs where we get all 0s */
 };
 
 /**