drm: Introduce drm_bridge_mode_valid()

Introduce a new helper function which calls mode_valid() callback
for all bridges in an encoder chain.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Carlos Palminha <palminha@synopsys.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Archit Taneja <architt@codeaurora.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/36bd5e054496ad3c9c71f1ffe204f28533f55f1e.1495720737.git.joabreu@synopsys.com

drivers/gpu/drm/drm_bridge.c

@@ -205,6 +205,39 @@ bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
 }
 EXPORT_SYMBOL(drm_bridge_mode_fixup);
 
+/**
+ * drm_bridge_mode_valid - validate the mode against all bridges in the
+ * 			   encoder chain.
+ * @bridge: bridge control structure
+ * @mode: desired mode to be validated
+ *
+ * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
+ * chain, starting from the first bridge to the last. If at least one bridge
+ * does not accept the mode the function returns the error code.
+ *
+ * Note: the bridge passed should be the one closest to the encoder.
+ *
+ * RETURNS:
+ * MODE_OK on success, drm_mode_status Enum error code on failure
+ */
+enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
+					   const struct drm_display_mode *mode)
+{
+	enum drm_mode_status ret = MODE_OK;
+
+	if (!bridge)
+		return ret;
+
+	if (bridge->funcs->mode_valid)
+		ret = bridge->funcs->mode_valid(bridge, mode);
+
+	if (ret != MODE_OK)
+		return ret;
+
+	return drm_bridge_mode_valid(bridge->next, mode);
+}
+EXPORT_SYMBOL(drm_bridge_mode_valid);
+
 /**
  * drm_bridge_disable - disables all bridges in the encoder chain
  * @bridge: bridge control structure

include/drm/drm_bridge.h

@@ -253,6 +253,8 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
 			const struct drm_display_mode *mode,
 			struct drm_display_mode *adjusted_mode);
+enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
+					   const struct drm_display_mode *mode);
 void drm_bridge_disable(struct drm_bridge *bridge);
 void drm_bridge_post_disable(struct drm_bridge *bridge);
 void drm_bridge_mode_set(struct drm_bridge *bridge,