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Old 03-29-2012, 05:20 PM
Colin Ian King
Default ACK: UBUNTU: SAUCE (no-up) Provide a param for allowing the BIOS to handle changing the brightness on AC/battery status changes.

On 29/03/12 16:53, Brad Figg wrote:

BugLink: http://bugs.launchpad.net/bugs/949311

We currently carry a SAUCE patch which lets the OS handle the brightness
levels automatically when connecting/disconnecting AC. There are some
laptops (MSI Wind) for which this doesn't work. Provide a driver param
which allows this behaviour to be overriden.

Signed-off-by: Brad Figg<brad.figg@canonical.com>
drivers/acpi/video.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index eae12b6..42b226e0 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -73,6 +73,14 @@ static int brightness_switch_enabled = 1;
module_param(brightness_switch_enabled, bool, 0644);

+ * The Default is to let the OS handle brightness autoswitching due to
+ * AC/battery status changes. On some laptops (MSI Wind) this doesn't
+ * work so we need a workaround.
+ */
+static int brightness_autoswitch_via_bios = 0;
+module_param(brightness_autoswitch_via_bios, bool, 0644);
* By default, we don't allow duplicate ACPI video bus devices
* under the same VGA controller
@@ -1421,7 +1429,7 @@ static int acpi_video_bus_put_devices(struct acpi_video_bus *video)

static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
- return acpi_video_bus_DOS(video, 0, 1);
+ return acpi_video_bus_DOS(video, 0, !brightness_autoswitch_via_bios);

static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)

It looks like a useful kludge around some broken firmware to get it
working, so yep, it does the necessary evil deed.

Acked-by: Colin Ian King <colin.king@canonical.com>

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