1 files changed, 180 insertions, 61 deletions

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 682359512996..bb427c5a4f1f 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -354,6 +354,79 @@ drm_helper_probe_detect(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_helper_probe_detect);
 
+static int drm_helper_probe_get_modes(struct drm_connector *connector)
+{
+	const struct drm_connector_helper_funcs *connector_funcs =
+		connector->helper_private;
+	int count;
+
+	count = connector_funcs->get_modes(connector);
+
+	/*
+	 * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
+	 * override/firmware EDID.
+	 */
+	if (count == 0 && connector->status == connector_status_connected)
+		count = drm_add_override_edid_modes(connector);
+
+	return count;
+}
+
+static int __drm_helper_update_and_validate(struct drm_connector *connector,
+					    uint32_t maxX, uint32_t maxY,
+					    struct drm_modeset_acquire_ctx *ctx)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_display_mode *mode;
+	int mode_flags = 0;
+	int ret;
+
+	drm_connector_list_update(connector);
+
+	if (connector->interlace_allowed)
+		mode_flags |= DRM_MODE_FLAG_INTERLACE;
+	if (connector->doublescan_allowed)
+		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
+	if (connector->stereo_allowed)
+		mode_flags |= DRM_MODE_FLAG_3D_MASK;
+
+	list_for_each_entry(mode, &connector->modes, head) {
+		if (mode->status != MODE_OK)
+			continue;
+
+		mode->status = drm_mode_validate_driver(dev, mode);
+		if (mode->status != MODE_OK)
+			continue;
+
+		mode->status = drm_mode_validate_size(mode, maxX, maxY);
+		if (mode->status != MODE_OK)
+			continue;
+
+		mode->status = drm_mode_validate_flag(mode, mode_flags);
+		if (mode->status != MODE_OK)
+			continue;
+
+		ret = drm_mode_validate_pipeline(mode, connector, ctx,
+						 &mode->status);
+		if (ret) {
+			drm_dbg_kms(dev,
+				    "drm_mode_validate_pipeline failed: %d\n",
+				    ret);
+
+			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK))
+				mode->status = MODE_ERROR;
+			else
+				return -EDEADLK;
+		}
+
+		if (mode->status != MODE_OK)
+			continue;
+		mode->status = drm_mode_validate_ycbcr420(mode, connector);
+	}
+
+	return 0;
+}
+
 /**
  * drm_helper_probe_single_connector_modes - get complete set of display modes
  * @connector: connector to probe
@@ -418,11 +491,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 {
 	struct drm_device *dev = connector->dev;
 	struct drm_display_mode *mode;
-	const struct drm_connector_helper_funcs *connector_funcs =
-		connector->helper_private;
 	int count = 0, ret;
-	int mode_flags = 0;
-	bool verbose_prune = true;
 	enum drm_connector_status old_status;
 	struct drm_modeset_acquire_ctx ctx;
 
@@ -502,74 +571,54 @@ retry:
 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
 			connector->base.id, connector->name);
 		drm_connector_update_edid_property(connector, NULL);
-		verbose_prune = false;
-		goto prune;
+		drm_mode_prune_invalid(dev, &connector->modes, false);
+		goto exit;
 	}
 
-	count = (*connector_funcs->get_modes)(connector);
-
-	/*
-	 * Fallback for when DDC probe failed in drm_get_edid() and thus skipped
-	 * override/firmware EDID.
-	 */
-	if (count == 0 && connector->status == connector_status_connected)
-		count = drm_add_override_edid_modes(connector);
+	count = drm_helper_probe_get_modes(connector);
 
 	if (count == 0 && (connector->status == connector_status_connected ||
-			   connector->status == connector_status_unknown))
+			   connector->status == connector_status_unknown)) {
 		count = drm_add_modes_noedid(connector, 1024, 768);
-	count += drm_helper_probe_add_cmdline_mode(connector);
-	if (count == 0)
-		goto prune;
 
-	drm_connector_list_update(connector);
-
-	if (connector->interlace_allowed)
-		mode_flags |= DRM_MODE_FLAG_INTERLACE;
-	if (connector->doublescan_allowed)
-		mode_flags |= DRM_MODE_FLAG_DBLSCAN;
-	if (connector->stereo_allowed)
-		mode_flags |= DRM_MODE_FLAG_3D_MASK;
-
-	list_for_each_entry(mode, &connector->modes, head) {
-		if (mode->status != MODE_OK)
-			continue;
-
-		mode->status = drm_mode_validate_driver(dev, mode);
-		if (mode->status != MODE_OK)
-			continue;
-
-		mode->status = drm_mode_validate_size(mode, maxX, maxY);
-		if (mode->status != MODE_OK)
-			continue;
-
-		mode->status = drm_mode_validate_flag(mode, mode_flags);
-		if (mode->status != MODE_OK)
-			continue;
+		/*
+		 * Section 4.2.2.6 (EDID Corruption Detection) of the DP 1.4a
+		 * Link CTS specifies that 640x480 (the official "failsafe"
+		 * mode) needs to be the default if there's no EDID.
+		 */
+		if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort)
+			drm_set_preferred_mode(connector, 640, 480);
+	}
+	count += drm_helper_probe_add_cmdline_mode(connector);
+	if (count != 0) {
+		ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
+		if (ret == -EDEADLK) {
+			drm_modeset_backoff(&ctx);
+			goto retry;
+		}
+	}
 
-		ret = drm_mode_validate_pipeline(mode, connector, &ctx,
-						 &mode->status);
-		if (ret) {
-			drm_dbg_kms(dev,
-				    "drm_mode_validate_pipeline failed: %d\n",
-				    ret);
+	drm_mode_prune_invalid(dev, &connector->modes, true);
 
-			if (drm_WARN_ON_ONCE(dev, ret != -EDEADLK)) {
-				mode->status = MODE_ERROR;
-			} else {
-				drm_modeset_backoff(&ctx);
-				goto retry;
-			}
+	/*
+	 * Displayport spec section 5.2.1.2 ("Video Timing Format") says that
+	 * all detachable sinks shall support 640x480 @60Hz as a fail safe
+	 * mode. If all modes were pruned, perhaps because they need more
+	 * lanes or a higher pixel clock than available, at least try to add
+	 * in 640x480.
+	 */
+	if (list_empty(&connector->modes) &&
+	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
+		count = drm_add_modes_noedid(connector, 640, 480);
+		ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
+		if (ret == -EDEADLK) {
+			drm_modeset_backoff(&ctx);
+			goto retry;
 		}
-
-		if (mode->status != MODE_OK)
-			continue;
-		mode->status = drm_mode_validate_ycbcr420(mode, connector);
+		drm_mode_prune_invalid(dev, &connector->modes, true);
 	}
 
-prune:
-	drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
-
+exit:
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
 
@@ -964,3 +1013,73 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
 	return changed;
 }
 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
+
+/**
+ * drm_connector_helper_get_modes_from_ddc - Updates the connector's EDID
+ *                                           property from the connector's
+ *                                           DDC channel
+ * @connector: The connector
+ *
+ * Returns:
+ * The number of detected display modes.
+ *
+ * Uses a connector's DDC channel to retrieve EDID data and update the
+ * connector's EDID property and display modes. Drivers can use this
+ * function to implement struct &drm_connector_helper_funcs.get_modes
+ * for connectors with a DDC channel.
+ */
+int drm_connector_helper_get_modes_from_ddc(struct drm_connector *connector)
+{
+	struct edid *edid;
+	int count = 0;
+
+	if (!connector->ddc)
+		return 0;
+
+	edid = drm_get_edid(connector, connector->ddc);
+
+	// clears property if EDID is NULL
+	drm_connector_update_edid_property(connector, edid);
+
+	if (edid) {
+		count = drm_add_edid_modes(connector, edid);
+		kfree(edid);
+	}
+
+	return count;
+}
+EXPORT_SYMBOL(drm_connector_helper_get_modes_from_ddc);
+
+/**
+ * drm_connector_helper_get_modes - Read EDID and update connector.
+ * @connector: The connector
+ *
+ * Read the EDID using drm_edid_read() (which requires that connector->ddc is
+ * set), and update the connector using the EDID.
+ *
+ * This can be used as the "default" connector helper .get_modes() hook if the
+ * driver does not need any special processing. This is sets the example what
+ * custom .get_modes() hooks should do regarding EDID read and connector update.
+ *
+ * Returns: Number of modes.
+ */
+int drm_connector_helper_get_modes(struct drm_connector *connector)
+{
+	const struct drm_edid *drm_edid;
+	int count;
+
+	drm_edid = drm_edid_read(connector);
+
+	/*
+	 * Unconditionally update the connector. If the EDID was read
+	 * successfully, fill in the connector information derived from the
+	 * EDID. Otherwise, if the EDID is NULL, clear the connector
+	 * information.
+	 */
+	count = drm_edid_connector_update(connector, drm_edid);
+
+	drm_edid_free(drm_edid);
+
+	return count;
+}
+EXPORT_SYMBOL(drm_connector_helper_get_modes);