From e5ed5676170c1ef7468a3f9073616dd54db302b7 Mon Sep 17 00:00:00 2001
From: Seth Forshee <seth.forshee@canonical.com>
Date: Fri, 20 Sep 2013 13:03:41 -0500
Subject: [PATCH] UBUNTU: SAUCE: (no-up) ACPI: Disable Windows 8 compatibility
 for some Lenovo ThinkPads

The AML implementation for brightness control on several ThinkPads
contains a workaround to meet a Windows 8 requirement of 101 brightness
levels [1]. The implementation is flawed, as only 16 of the brighness
values reported by _BCL affect a change in brightness. _BCM silently
discards the rest of the values. Disabling Windows 8 compatibility on
these machines reverts them to the old behavior, making _BCL only report
the 16 brightness levels which actually work. Add a quirk to do this
along with a dmi callback to disable Win8 compatibility.

[1] http://msdn.microsoft.com/en-us/library/windows/hardware/jj128256.aspx

BugLink: http://bugs.launchpad.net/bugs/1183856
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 drivers/acpi/osi.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/drivers/acpi/osi.c b/drivers/acpi/osi.c
index df9328c850bd..956f7fe403a3 100644
--- a/drivers/acpi/osi.c
+++ b/drivers/acpi/osi.c
@@ -443,6 +443,77 @@ static const struct dmi_system_id acpi_osi_dmi_table[] __initconst = {
 		},
 	},
 
+	/*
+	 * The following Lenovo models have a broken workaround in the
+	 * acpi_video backlight implementation to meet the Windows 8
+	 * requirement of 101 backlight levels. Reverting to pre-Win8
+	 * behavior fixes the problem.
+	 */
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad L430",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad L430"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad T430",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T430"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad T430s",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T430s"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad T530",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T530"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad W530",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad W530"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad X1 Carbon",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X1 Carbon"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad X230",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X230"),
+		},
+	},
+	{
+	.callback = dmi_disable_osi_win8,
+	.ident = "Lenovo ThinkPad Edge E330",
+	.matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad Edge E330"),
+		},
+	},
+
 	/*
 	 * BIOS invocation of _OSI(Linux) is almost always a BIOS bug.
 	 * Linux ignores it, except for the machines enumerated below.