From dba266834b0ed53c3380b4ad84bb59134ab1a604 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Wed, 14 Mar 2012 18:37:04 +1100
Subject: [PATCH] --- yaml --- r: 292535 b: refs/heads/master c:
 7d3d897a4697e4ff746e5e82f116b2346ed28150 h: refs/heads/master i:   292533:
 fb3a03767424e5d268644e2d56f2cedcf99058d3   292531:
 4e5496d3654cb9e83a3232a0c45f7aeedef8095c   292527:
 df41c5b0b8484f7b84f723abfe0b1aa6f70c1c97 v: v3

---
 [refs]                           | 2 +-
 trunk/drivers/tty/hvc/Kconfig    | 4 ++++
 trunk/drivers/tty/hvc/hvc_udbg.c | 8 +++++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 8f9c4536e0c1..ea571f4b16db 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ba7a4822b48fbc7afd6b567c18e316a03f46684d
+refs/heads/master: 7d3d897a4697e4ff746e5e82f116b2346ed28150
diff --git a/trunk/drivers/tty/hvc/Kconfig b/trunk/drivers/tty/hvc/Kconfig
index 8ea7f078b233..48cb8d3d1758 100644
--- a/trunk/drivers/tty/hvc/Kconfig
+++ b/trunk/drivers/tty/hvc/Kconfig
@@ -71,6 +71,10 @@ config HVC_UDBG
        depends on PPC && EXPERIMENTAL
        select HVC_DRIVER
        default n
+       help
+         This is meant to be used during HW bring up or debugging when
+	 no other console mechanism exist but udbg, to get you a quick
+	 console for userspace. Do NOT enable in production kernels. 
 
 config HVC_DCC
        bool "ARM JTAG DCC console"
diff --git a/trunk/drivers/tty/hvc/hvc_udbg.c b/trunk/drivers/tty/hvc/hvc_udbg.c
index b0957e61a7be..2259c6e72f06 100644
--- a/trunk/drivers/tty/hvc/hvc_udbg.c
+++ b/trunk/drivers/tty/hvc/hvc_udbg.c
@@ -36,7 +36,7 @@ static int hvc_udbg_put(uint32_t vtermno, const char *buf, int count)
 {
 	int i;
 
-	for (i = 0; i < count; i++)
+	for (i = 0; i < count && udbg_putc; i++)
 		udbg_putc(buf[i]);
 
 	return i;
@@ -67,6 +67,9 @@ static int __init hvc_udbg_init(void)
 {
 	struct hvc_struct *hp;
 
+	if (!udbg_putc)
+		return -ENODEV;
+
 	BUG_ON(hvc_udbg_dev);
 
 	hp = hvc_alloc(0, NO_IRQ, &hvc_udbg_ops, 16);
@@ -88,6 +91,9 @@ module_exit(hvc_udbg_exit);
 
 static int __init hvc_udbg_console_init(void)
 {
+	if (!udbg_putc)
+		return -ENODEV;
+
 	hvc_instantiate(0, 0, &hvc_udbg_ops);
 	add_preferred_console("hvc", 0, NULL);