[PATCH v4 19/31] platform/x86: nvidia-wmi-ec-backlight: Use acpi_video_get_backlight_type()

Hans de Goede
2022-08-24T12:17:41Z

Add an acpi_video_get_backlight_type() == acpi_backlight_nvidia_wmi_ec
check. This will make nvidia-wmi-ec-backlight properly honor the user
selecting a different backlight driver through the acpi_backlight=...
kernel commandline option.

Since the auto-detect code check for nvidia-wmi-ec-backlight in
drivers/acpi/video_detect.c already checks that the WMI advertised
brightness-source is the embedded controller, this new check makes it
unnecessary for nvidia_wmi_ec_backlight_probe() to check this itself.

Suggested-by: Daniel Dadap <ddadap@nvidia.com>
Reviewed-by: Daniel Dadap <ddadap@nvidia.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/platform/x86/Kconfig | 1 +
drivers/platform/x86/nvidia-wmi-ec-backlight.c | 14 +++-----------
2 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index f2f98e942cf2..0cc5ac35fc57 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -93,6 +93,7 @@ config PEAQ_WMI

config NVIDIA_WMI_EC_BACKLIGHT
tristate "EC Backlight Driver for Hybrid Graphics Notebook Systems"
+ depends on ACPI_VIDEO
depends on ACPI_WMI
depends on BACKLIGHT_CLASS_DEVICE
help
diff --git a/drivers/platform/x86/nvidia-wmi-ec-backlight.c b/drivers/platform/x86/nvidia-wmi-ec-backlight.c
index be803e47eac0..baccdf658538 100644
--- a/drivers/platform/x86/nvidia-wmi-ec-backlight.c
+++ b/drivers/platform/x86/nvidia-wmi-ec-backlight.c
@@ -10,6 +10,7 @@
#include <linux/platform_data/x86/nvidia-wmi-ec-backlight.h>
#include <linux/types.h>
#include <linux/wmi.h>
+#include <acpi/video.h>

/**
* wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
@@ -87,19 +88,10 @@ static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ct
{
struct backlight_properties props = {};
struct backlight_device *bdev;
- u32 source;
int ret;

- ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_SOURCE,
- WMI_BRIGHTNESS_MODE_GET, &source);
- if (ret)
- return ret;
-
- /*
- * This driver is only to be used when brightness control is handled
- * by the EC; otherwise, the GPU driver(s) should control brightness.
- */
- if (source != WMI_BRIGHTNESS_SOURCE_EC)
+ /* drivers/acpi/video_detect.c also checks that SOURCE == EC */
+ if (acpi_video_get_backlight_type() != acpi_backlight_nvidia_wmi_ec)
return -ENODEV;

/*
--
2.37.2