diff options
Diffstat (limited to 'drivers/platform/x86/apple-gmux.c')
| -rw-r--r-- | drivers/platform/x86/apple-gmux.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index cadbb557a108..1417e230edbd 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -105,6 +105,8 @@ struct apple_gmux_config { #define GMUX_BRIGHTNESS_MASK 0x00ffffff #define GMUX_MAX_BRIGHTNESS GMUX_BRIGHTNESS_MASK +# define MMIO_GMUX_MAX_BRIGHTNESS 0xffff + static u8 gmux_pio_read8(struct apple_gmux_data *gmux_data, int port) { return inb(gmux_data->iostart + port); @@ -857,7 +859,17 @@ get_version: memset(&props, 0, sizeof(props)); props.type = BACKLIGHT_PLATFORM; - props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); + + /* + * All MMIO gmux's have 0xffff as max brightness, but some iMacs incorrectly + * report 0x03ff, despite the firmware being happy to set 0xffff as the brightness + * at boot. Force 0xffff for all MMIO gmux's so they all have the correct brightness + * range. + */ + if (type == APPLE_GMUX_TYPE_MMIO) + props.max_brightness = MMIO_GMUX_MAX_BRIGHTNESS; + else + props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); #if IS_REACHABLE(CONFIG_ACPI_VIDEO) register_bdev = acpi_video_get_backlight_type() == acpi_backlight_apple_gmux; |