soc: amlogic: canvas: Fix meson_canvas_get when probe failed

When probe fails, a platforn_device is still associated to the node,
but dev_get_drvdata() returns NULL.

Handle this case by returning a consistent error.

Fixes: d4983983d9 ("soc: amlogic: add meson-canvas driver")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Maxime Jourdan <mjourdan@baylibre.com>
[khilman: fixed minor typo in comment ]
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

drivers/soc/amlogic/meson-canvas.c

@@ -51,6 +51,7 @@ struct meson_canvas *meson_canvas_get(struct device *dev)
 {
 	struct device_node *canvas_node;
 	struct platform_device *canvas_pdev;
+	struct meson_canvas *canvas;
 
 	canvas_node = of_parse_phandle(dev->of_node, "amlogic,canvas", 0);
 	if (!canvas_node)
@@ -63,7 +64,17 @@ struct meson_canvas *meson_canvas_get(struct device *dev)
 	}
 
 	of_node_put(canvas_node);
-	return dev_get_drvdata(&canvas_pdev->dev);
+
+	/*
+	 * If priv is NULL, it's probably because the canvas hasn't
+	 * properly initialized. Bail out with -EINVAL because, in the
+	 * current state, this driver probe cannot return -EPROBE_DEFER
+	 */
+	canvas = dev_get_drvdata(&canvas_pdev->dev);
+	if (!canvas)
+		return ERR_PTR(-EINVAL);
+
+	return canvas;
 }
 EXPORT_SYMBOL_GPL(meson_canvas_get);