Make apple-gmux backlight registration honor the acpi_backlight=... kernel commandline option which is used to select the backlight control method on x86/ACPI devices. Reported-and-tested-by: Aditya Garg <gargaditya08@xxxxxxxx> Link: https://lore.kernel.org/platform-driver-x86/BM1PR01MB0931B467250831916F7C55B3B8A59@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/platform/x86/apple-gmux.c | 59 +++++++++++++++++-------------- 1 file changed, 33 insertions(+), 26 deletions(-) diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 757fd71c900f..787cf2a7e268 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -23,6 +23,7 @@ #include <linux/pci.h> #include <linux/vga_switcheroo.h> #include <linux/debugfs.h> +#include <acpi/video.h> #include <asm/io.h> /** @@ -783,6 +784,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) struct backlight_properties props; struct backlight_device *bdev; u8 ver_major, ver_minor, ver_release; + bool register_bdev = true; int ret = -ENXIO; acpi_status status; unsigned long long gpe; @@ -859,33 +861,38 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) props.type = BACKLIGHT_PLATFORM; props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); - /* - * Currently it's assumed that the maximum brightness is less than - * 2^24 for compatibility with old gmux versions. Cap the max - * brightness at this value, but print a warning if the hardware - * reports something higher so that it can be fixed. - */ - if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS)) - props.max_brightness = GMUX_MAX_BRIGHTNESS; - - bdev = backlight_device_register("gmux_backlight", &pnp->dev, - gmux_data, &gmux_bl_ops, &props); - if (IS_ERR(bdev)) { - ret = PTR_ERR(bdev); - goto err_unmap; - } - - gmux_data->bdev = bdev; - bdev->props.brightness = gmux_get_brightness(bdev); - backlight_update_status(bdev); +#if IS_REACHABLE(CONFIG_ACPI_VIDEO) + register_bdev = acpi_video_get_backlight_type() == acpi_backlight_apple_gmux; +#endif + if (register_bdev) { + /* + * Currently it's assumed that the maximum brightness is less than + * 2^24 for compatibility with old gmux versions. Cap the max + * brightness at this value, but print a warning if the hardware + * reports something higher so that it can be fixed. + */ + if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS)) + props.max_brightness = GMUX_MAX_BRIGHTNESS; + + bdev = backlight_device_register("gmux_backlight", &pnp->dev, + gmux_data, &gmux_bl_ops, &props); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + goto err_unmap; + } - /* - * The backlight situation on Macs is complicated. If the gmux is - * present it's the best choice, because it always works for - * backlight control and supports more levels than other options. - * Disable the other backlight choices. - */ - apple_bl_unregister(); + gmux_data->bdev = bdev; + bdev->props.brightness = gmux_get_brightness(bdev); + backlight_update_status(bdev); + + /* + * The backlight situation on Macs is complicated. If the gmux is + * present it's the best choice, because it always works for + * backlight control and supports more levels than other options. + * Disable the other backlight choices. + */ + apple_bl_unregister(); + } gmux_data->power_state = VGA_SWITCHEROO_ON; -- 2.39.1
