[PATCH v5 0/4] Fix Win8 backlight issue

[Aaron Lu]

On 10/28/2013 04:09 PM, Jani Nikula wrote:
> On Mon, 28 Oct 2013, Aaron Lu <aaron.lu at intel.com> wrote:
>> +static int __init video_set_use_native_backlight(const struct dmi_system_id *d)
>> +{
>> +	use_native_backlight = true;
>> +	return 0;
>> +}
> 
> Hi Aaron, it might be beneficial to make use_native_backlight support
> three values: force true, force false, and use platform default based on
> DMI.

Makes sense. I modified the patch a little bit so that if user has
specified the cmdline option use_native_backlight=0/1, it will always
take effect no matter if the system is in DMI table or not.

From: Aaron Lu <aaron.lu at intel.com>
Subject: [PATCH] ACPI / video: Add systems that should favor native backlight
 interface

Some system's ACPI video backlight control interface is broken and the
native backlight control interface should be used by default. This patch
sets the use_native_backlight parameter to true for those systems so
that video backlight control interface will not be created. To be
specific, the ThinkPad T430s/X230, Lenovo Yoga 13 and Dell Inspiron 7520
are added here.

Note that the user specified kernel cmdline option will always have the
highest priority, i.e. if use_native_backlight=0 is specified and the
system is in the DMI table, the video module will not skip register
backlight interface for it.

Thinkpad T430s:
Reported-by: Theodore Tso <tytso at mit.edu>
Reported-and-tested-by: Peter Weber <bugs at ttyhoney.com>
Thinkpad X230:
Reported-and-tested-by: Igor Gnatenko <i.gnatenko.brain at gmail.com>
Lenovo Yoga 13:
Reported-by: Lennart Poettering <lennart at poettering.net>
Reported-and-tested-by: Kevin Smith <thirdwiggin at gmail.com>
Dell Inspiron 7520:
Reported-by: Rinat Ibragimov <ibragimovrinat at mail.ru>

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=51231
Signed-off-by: Aaron Lu <aaron.lu at intel.com>
---
 drivers/acpi/video.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 38c3a28..41bd4b4 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -89,11 +89,12 @@ static bool use_bios_initial_backlight = 1;
 module_param(use_bios_initial_backlight, bool, 0644);
 
 /*
- * For Windows 8 systems: if set ture and the GPU driver has
- * registered a backlight interface, skip registering ACPI video's.
+ * For Windows 8 systems: used to decide if video module
+ * should skip registering backlight interface of its own.
  */
-static bool use_native_backlight = false;
-module_param(use_native_backlight, bool, 0644);
+static int use_native_backlight_param = -1;
+module_param_named(use_native_backlight, use_native_backlight_param, int, 0444);
+static bool use_native_backlight_dmi = false;
 
 static int register_count;
 static struct mutex video_list_lock;
@@ -239,9 +240,17 @@ static int acpi_video_get_next_level(struct acpi_video_device *device,
 static int acpi_video_switch_brightness(struct acpi_video_device *device,
 					 int event);
 
+static bool acpi_video_use_native_backlight(void)
+{
+	if (use_native_backlight_param != -1)
+		return !!use_native_backlight_param;
+	else
+		return use_native_backlight_dmi;
+}
+
 static bool acpi_video_verify_backlight_support(void)
 {
-	if (acpi_osi_is_win8() && use_native_backlight &&
+	if (acpi_osi_is_win8() && acpi_video_use_native_backlight() &&
 	    backlight_device_registered(BACKLIGHT_RAW))
 		return false;
 	return acpi_video_backlight_support();
@@ -412,6 +421,12 @@ static int video_ignore_initial_backlight(const struct dmi_system_id *d)
 	return 0;
 }
 
+static int __init video_set_use_native_backlight(const struct dmi_system_id *d)
+{
+	use_native_backlight_dmi = true;
+	return 0;
+}
+
 static struct dmi_system_id video_dmi_table[] __initdata = {
 	/*
 	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
@@ -512,6 +527,38 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
 		DMI_MATCH(DMI_PRODUCT_NAME, "HP 250 G1 Notebook PC"),
 		},
 	},
+	{
+	 .callback = video_set_use_native_backlight,
+	 .ident = "ThinkPad T430s",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T430s"),
+		},
+	},
+	{
+	 .callback = video_set_use_native_backlight,
+	 .ident = "ThinkPad X230",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X230"),
+		},
+	},
+	{
+	 .callback = video_set_use_native_backlight,
+	 .ident = "Lenovo Yoga 13",
+	 .matches = {
+		 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		 DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo IdeaPad Yoga 13"),
+		},
+	},
+	{
+	 .callback = video_set_use_native_backlight,
+	 .ident = "Dell Inspiron 7520",
+	 .matches = {
+		 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+		 DMI_MATCH(DMI_PRODUCT_VERSION, "Inspiron 7520"),
+		},
+	},
 	{}
 };
 
-- 
1.8.4.39.ga0d3f10