Thanks, Hans. The new commit message sounds more appropriate.
Reviewed-by: Daniel Dadap <ddadap@xxxxxxxxxx>
On Fri, Feb 17, 2023 at 03:42:08PM +0100, Hans de Goede wrote:
> On some Lenovo Legion models, the backlight might be driven by either
> one of nvidia_wmi_ec_backlight or amdgpu_bl0 at different times.
>
> When the Nvidia WMI EC backlight interface reports the backlight is
> controlled by the EC, the current backlight handling only registers
> nvidia_wmi_ec_backlight (and registers no other backlight interfaces).
>
> This hides (never registers) the amdgpu_bl0 interface, where as prior
> to 6.1.4 users would have both nvidia_wmi_ec_backlight and amdgpu_bl0
> and could work around things in userspace.
>
> Add a force module parameter which can be used with acpi_backlight=native
> to restore the old behavior as a workound (for now) by passing:
>
> "acpi_backlight=native nvidia-wmi-ec-backlight.force=1"
>
> Fixes: 8d0ca287fd8c ("platform/x86: nvidia-wmi-ec-backlight: Use acpi_video_get_backlight_type()")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217026
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> Changes in v2:
> - Reword commit message
> ---
> drivers/platform/x86/nvidia-wmi-ec-backlight.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/nvidia-wmi-ec-backlight.c b/drivers/platform/x86/nvidia-wmi-ec-backlight.c
> index baccdf658538..1b572c90c76e 100644
> --- a/drivers/platform/x86/nvidia-wmi-ec-backlight.c
> +++ b/drivers/platform/x86/nvidia-wmi-ec-backlight.c
> @@ -12,6 +12,10 @@
> #include <linux/wmi.h>
> #include <acpi/video.h>
>
> +static bool force;
> +module_param(force, bool, 0444);
> +MODULE_PARM_DESC(force, "Force loading (disable acpi_backlight=xxx checks");
> +
> /**
> * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
> * @w: Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID
> @@ -91,7 +95,7 @@ static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ct
> int ret;
>
> /* drivers/acpi/video_detect.c also checks that SOURCE == EC */
> - if (acpi_video_get_backlight_type() != acpi_backlight_nvidia_wmi_ec)
> + if (!force && acpi_video_get_backlight_type() != acpi_backlight_nvidia_wmi_ec)
> return -ENODEV;
>
> /*
> --
> 2.39.1
>
