From: Hans de Goede <hdegoede@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Reviewed-by: Daniel Dadap <ddadap@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230217144208.5721-1-hdegoede@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
/*
