[PATCH] Enable A20 using KBC for some MSI laptops to fix S3 resume

[Ondrej Zary <linux@rainbow-software.org>]

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. Affected laptop list and DMI data are from
bug reports at Ubuntu Launchpad.

Tested with EX600 and PR200.

Fixes https://bugzilla.kernel.org/show_bug.cgi?id=12878

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>

--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1349,6 +1349,20 @@ static int __init dmi_ignore_irq0_timer_override(const struct dmi_system_id *d)
 }
 
 /*
+ * Enable A20 line using KBC even if it's already enabled using other method.
+ * This is needed for some MSI laptops to resume from S3.
+ */
+static int __init a20_enable_kbc(const struct dmi_system_id *d)
+{
+	printk(KERN_NOTICE "%s detected: enabling A20 using KBC\n", d->ident);
+	outb(0xd1, 0x64);	/* Command write */
+	outb(0xdf, 0x60);	/* A20 on */
+	outb(0xff, 0x64);	/* Null command, but UHCI wants it */
+
+	return 0;
+}
+
+/*
  * If your system is blacklisted here, but you find that acpi=force
  * works for you, please contact linux-acpi@vger.kernel.org
  */
@@ -1423,6 +1437,60 @@ static struct dmi_system_id __initdata acpi_dmi_table[] = {
 		     DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 360"),
 		     },
 	 },
+	/*
+	 * 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.
+	 */
+	{
+	 .callback = a20_enable_kbc,
+	 .ident = "MSI EX600 Laptop",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star International"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "MSI Notebook EX600"),
+		     },
+	 },
+	{
+	 .callback = a20_enable_kbc,
+	 .ident = "MSI EX700 Laptop",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star International"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "EX700"),
+		     },
+	 },
+	{
+	 .callback = a20_enable_kbc,
+	 .ident = "MSI GX700 Laptop",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star International"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "GX700"),
+		     },
+	 },
+	{
+	 .callback = a20_enable_kbc,
+	 .ident = "MSI VR201 Laptop",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star International"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "MSI Notebook VR201"),
+		     },
+	 },
+	{
+	 .callback = a20_enable_kbc,
+	 .ident = "MSI VR601 Laptop",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star International"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "MSI Notebook VR601"),
+		     },
+	 },
+	{
+	 .callback = a20_enable_kbc,
+	 .ident = "MSI PR200 Laptop",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star International"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "MSI Notebook PR200"),
+		     },
+	 },
 	{}
 };
 


-- 
Ondrej Zary