[PATCH] acpi-video: Fix brightness keys for Thinkpad X240

[Mathieu OTHACEHE <m.othacehe@gmail.com>]

Thinkpad X240 laptop has a working acpi_video backlight control but
using the default native backlight control, brightness keys does not work.

This patch force acpi_video use for this laptop by adding an exception in
video_detect_dmi_table.

Signed-off-by: Mathieu OTHACEHE <m.othacehe@gmail.com>
---
 drivers/acpi/video_detect.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 815f75e..c4bc5f2 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -173,6 +173,14 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
 		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
 		},
 	},
+	{
+	 .callback = video_detect_force_video,
+	 .ident = "ThinkPad X240",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X240"),
+		},
+	},
 
 	/* The native backlight controls do not work on some older machines */
 	{
-- 
2.4.5