Patchwork [3.5.y.z,extended,stable] Patch "x86, 8042: Enable A20 using KBC to fix S3 resume on" has been added to staging queue

mail settings
Submitter Herton Ronaldo Krzesinski
Date Jan. 8, 2013, 8:57 p.m.
Message ID <>
Download mbox | patch
Permalink /patch/210508/
State New
Headers show


Herton Ronaldo Krzesinski - Jan. 8, 2013, 8:57 p.m.
This is a note to let you know that I have just added a patch titled

    x86, 8042: Enable A20 using KBC to fix S3 resume on

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



From 1c2a54da3ff8be8d21aebf1d6fc5e5a91d2098af Mon Sep 17 00:00:00 2001
From: Ondrej Zary <>
Date: Tue, 11 Dec 2012 22:18:05 +0100
Subject: [PATCH 09/27] x86, 8042: Enable A20 using KBC to fix S3 resume on
 some MSI laptops

commit ad68652412276f68ad4fe3e1ecf5ee6880876783 upstream.

Some MSI laptop BIOSes are broken - INT 15h code uses port 92h to enable A20
line but resume code assumes that KBC was used.
The laptop will not resume from S3 otherwise but powers off after a while
and then powers on again stuck with a blank screen.

Fix it by enabling A20 using KBC in i8042_platform_init for x86.


Signed-off-by: Ondrej Zary <>
Cc: Dmitry Torokhov <>
Cc: Alan Cox <>
Cc: Rafael J. Wysocki <>
Signed-off-by: H. Peter Anvin <>
Signed-off-by: Herton Ronaldo Krzesinski <>
 drivers/input/serio/i8042-x86ia64io.h |    9 +++++++++
 1 file changed, 9 insertions(+)



diff --git a/drivers/input/serio/i8042-x86ia64io.h b/drivers/input/serio/i8042-x86ia64io.h
index d6cc77a..5f306f7 100644
--- a/drivers/input/serio/i8042-x86ia64io.h
+++ b/drivers/input/serio/i8042-x86ia64io.h
@@ -921,6 +921,7 @@  static int __init i8042_platform_init(void)
 	int retval;

 #ifdef CONFIG_X86
+	u8 a20_on = 0xdf;
 	/* Just return if pre-detection shows no i8042 controller exist */
 	if (!x86_platform.i8042_detect())
 		return -ENODEV;
@@ -960,6 +961,14 @@  static int __init i8042_platform_init(void)

 	if (dmi_check_system(i8042_dmi_dritek_table))
 		i8042_dritek = true;
+	/*
+	 * A20 was already enabled during early kernel init. But some buggy
+	 * BIOSes (in MSI Laptops) require A20 to be enabled using 8042 to
+	 * resume from S3. So we do it here and hope that nothing breaks.
+	 */
+	i8042_command(&a20_on, 0x10d1);
+	i8042_command(NULL, 0x00ff);	/* Null command for SMM firmware */
 #endif /* CONFIG_X86 */

 	return retval;