video: Show an error when a vidconsole function fails

At present these functions fail silently even when debugging, which is not
very helpful. Add a way to print a message to the serial output when an
error is detected.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/video/vidconsole-uclass.c b/drivers/video/vidconsole-uclass.c
index 3f20f70..841cfda 100644
--- a/drivers/video/vidconsole-uclass.c
+++ b/drivers/video/vidconsole-uclass.c
@@ -9,12 +9,13 @@
 
 #include <common.h>
 #include <command.h>
+#include <console.h>
 #include <log.h>
-#include <linux/ctype.h>
 #include <dm.h>
 #include <video.h>
 #include <video_console.h>
 #include <video_font.h>		/* Bitmap font for code page 437 */
+#include <linux/ctype.h>
 
 /*
  * Structure to describe a console color
@@ -556,16 +557,31 @@
 static void vidconsole_putc(struct stdio_dev *sdev, const char ch)
 {
 	struct udevice *dev = sdev->priv;
+	int ret;
 
-	vidconsole_put_char(dev, ch);
+	ret = vidconsole_put_char(dev, ch);
+	if (ret) {
+#ifdef DEBUG
+		console_puts_select_stderr(true, "[vc err: putc]");
+#endif
+	}
 	video_sync(dev->parent, false);
 }
 
 static void vidconsole_puts(struct stdio_dev *sdev, const char *s)
 {
 	struct udevice *dev = sdev->priv;
+	int ret;
 
-	vidconsole_put_string(dev, s);
+	ret = vidconsole_put_string(dev, s);
+	if (ret) {
+#ifdef DEBUG
+		char str[30];
+
+		snprintf(str, sizeof(str), "[vc err: puts %d]", ret);
+		console_puts_select_stderr(true, str);
+#endif
+	}
 	video_sync(dev->parent, false);
 }