From: Hans de Goede hdegoede@redhat.com
commit 0d9bdd8a550170306c2021b8d6766c5343b870c2 upstream.
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 Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede hdegoede@redhat.com Reviewed-by: Daniel Dadap ddadap@nvidia.com Link: https://lore.kernel.org/r/20230217144208.5721-1-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/platform/x86/nvidia-wmi-ec-backlight.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- 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 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;
/*