diff --git a/arch/arm/mach-tegra/include/mach/uncompress.h b/arch/arm/mach-tegra/include/mach/uncompress.h
index bb3fd359f9fad451d85402e775dfbef72f63c2b3..6c087b6974b249d09f04743c6f0b6165f0a81299 100644
--- a/arch/arm/mach-tegra/include/mach/uncompress.h
+++ b/arch/arm/mach-tegra/include/mach/uncompress.h
@@ -3,11 +3,13 @@
  *
  * Copyright (C) 2010 Google, Inc.
  * Copyright (C) 2011 Google, Inc.
+ * Copyright (C) 2011 NVIDIA CORPORATION. All Rights Reserved.
  *
  * Author:
  *	Colin Cross <ccross@google.com>
  *	Erik Gilling <konkers@google.com>
  *	Doug Anderson <dianders@chromium.org>
+ *	Stephen Warren <swarren@nvidia.com>
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -23,6 +25,7 @@
 #ifndef __MACH_TEGRA_UNCOMPRESS_H
 #define __MACH_TEGRA_UNCOMPRESS_H
 
+#include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/serial_reg.h>
 
@@ -46,12 +49,82 @@ static inline void flush(void)
 {
 }
 
+/*
+ * Setup before decompression.  This is where we do UART selection for
+ * earlyprintk and init the uart_base register.
+ */
 static inline void arch_decomp_setup(void)
 {
+	static const struct {
+		u32 base;
+		u32 reset_reg;
+		u32 clock_reg;
+		u32 bit;
+	} uarts[] = {
+		{
+			TEGRA_UARTA_BASE,
+			TEGRA_CLK_RESET_BASE + 0x04,
+			TEGRA_CLK_RESET_BASE + 0x10,
+			6,
+		},
+		{
+			TEGRA_UARTB_BASE,
+			TEGRA_CLK_RESET_BASE + 0x04,
+			TEGRA_CLK_RESET_BASE + 0x10,
+			7,
+		},
+		{
+			TEGRA_UARTC_BASE,
+			TEGRA_CLK_RESET_BASE + 0x08,
+			TEGRA_CLK_RESET_BASE + 0x14,
+			23,
+		},
+		{
+			TEGRA_UARTD_BASE,
+			TEGRA_CLK_RESET_BASE + 0x0c,
+			TEGRA_CLK_RESET_BASE + 0x18,
+			1,
+		},
+		{
+			TEGRA_UARTE_BASE,
+			TEGRA_CLK_RESET_BASE + 0x0c,
+			TEGRA_CLK_RESET_BASE + 0x18,
+			2,
+		},
+	};
+	int i;
 	volatile u32 *apb_misc = (volatile u32 *)TEGRA_APB_MISC_BASE;
 	u32 chip, div;
 
-	uart = (volatile u8 *)TEGRA_DEBUG_UART_BASE;
+	/*
+	 * Look for the first UART that:
+	 * a) Is not in reset.
+	 * b) Is clocked.
+	 * c) Has a 'D' in the scratchpad register.
+	 *
+	 * Note that on Tegra30, the first two conditions are required, since
+	 * if not true, accesses to the UART scratch register will hang.
+	 * Tegra20 doesn't have this issue.
+	 *
+	 * The intent is that the bootloader will tell the kernel which UART
+	 * to use by setting up those conditions. If nothing found, we'll fall
+	 * back to what's specified in TEGRA_DEBUG_UART_BASE.
+	 */
+	for (i = 0; i < ARRAY_SIZE(uarts); i++) {
+		if (*(u8 *)uarts[i].reset_reg & BIT(uarts[i].bit))
+			continue;
+
+		if (!(*(u8 *)uarts[i].clock_reg & BIT(uarts[i].bit)))
+			continue;
+
+		uart = (volatile u8 *)uarts[i].base;
+		if (uart[UART_SCR << DEBUG_UART_SHIFT] != 'D')
+			continue;
+
+		break;
+	}
+	if (i == ARRAY_SIZE(uarts))
+		uart = (volatile u8 *)TEGRA_DEBUG_UART_BASE;
 	if (uart == NULL)
 		return;