[patch 4/8] platform: samsung_laptop: fix samsung brightness min/max calculations

gregkh
2011-09-01T22:56:22Z

From: Jason Stubbs <jasonbstubbs@gmail.com>

The min_brightness value of the sabi_config is incorrectly used in brightness
calculations. For the config where min_brightness = 1 and max_brightness = 8,
the user visible range should be 0 to 7 with hardware being set in the range
of 1 to 8. What is actually happening is that the user visible range is 0 to
8 with hardware being set in the range of -1 to 7.

This patch fixes the above issue as well as a miscalculation that would occur
in the case of min_brightness > 1.

Signed-off-by: Jason Stubbs <jasonbstubbs@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/platform/x86/samsung-laptop.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/platform/x86/samsung-laptop.c
+++ b/drivers/platform/x86/samsung-laptop.c
@@ -370,15 +370,17 @@ static u8 read_brightness(void)
&sretval);
if (!retval) {
user_brightness = sretval.retval[0];
- if (user_brightness != 0)
+ if (user_brightness > sabi_config->min_brightness)
user_brightness -= sabi_config->min_brightness;
+ else
+ user_brightness = 0;
}
return user_brightness;
}

static void set_brightness(u8 user_brightness)
{
- u8 user_level = user_brightness - sabi_config->min_brightness;
+ u8 user_level = user_brightness + sabi_config->min_brightness;

sabi_set_command(sabi_config->commands.set_brightness, user_level);
}
@@ -829,7 +831,8 @@ static int __init samsung_init(void)
/* create a backlight device to talk to this one */
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_PLATFORM;
- props.max_brightness = sabi_config->max_brightness;
+ props.max_brightness = sabi_config->max_brightness -
+ sabi_config->min_brightness;
backlight_device = backlight_device_register("samsung", &sdev->dev,
NULL, &backlight_ops,
&props);