diff options
Diffstat (limited to 'drivers/platform/x86/samsung-laptop.c')
| -rw-r--r-- | drivers/platform/x86/samsung-laptop.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c index 4d3bed476d52..6474e426dae9 100644 --- a/drivers/platform/x86/samsung-laptop.c +++ b/drivers/platform/x86/samsung-laptop.c @@ -226,6 +226,7 @@ static struct backlight_device *backlight_device; static struct mutex sabi_mutex; static struct platform_device *sdev; static struct rfkill *rfk; +static bool has_stepping_quirk; static int force; module_param(force, bool, 0); @@ -382,6 +383,17 @@ static void set_brightness(u8 user_brightness) { u8 user_level = user_brightness + sabi_config->min_brightness; + if (has_stepping_quirk && user_level != 0) { + /* + * short circuit if the specified level is what's already set + * to prevent the screen from flickering needlessly + */ + if (user_brightness == read_brightness()) + return; + + sabi_set_command(sabi_config->commands.set_brightness, 0); + } + sabi_set_command(sabi_config->commands.set_brightness, user_level); } @@ -390,6 +402,34 @@ static int get_brightness(struct backlight_device *bd) return (int)read_brightness(); } +static void check_for_stepping_quirk(void) +{ + u8 initial_level = read_brightness(); + u8 check_level; + + /* + * Some laptops exhibit the strange behaviour of stepping toward + * (rather than setting) the brightness except when changing to/from + * brightness level 0. This behaviour is checked for here and worked + * around in set_brightness. + */ + + if (initial_level <= 2) + check_level = initial_level + 2; + else + check_level = initial_level - 2; + + has_stepping_quirk = false; + set_brightness(check_level); + + if (read_brightness() != check_level) { + has_stepping_quirk = true; + pr_info("enabled workaround for brightness stepping quirk\n"); + } + + set_brightness(initial_level); +} + static int update_status(struct backlight_device *bd) { set_brightness(bd->props.brightness); @@ -805,6 +845,9 @@ static int __init samsung_init(void) } } + /* Check for stepping quirk */ + check_for_stepping_quirk(); + /* knock up a platform device to hang stuff off of */ sdev = platform_device_register_simple("samsung", -1, NULL, 0); if (IS_ERR(sdev)) |