/usr/ports/graphics/drm-515-kmod/work/drm-kmod-drm_v5.15.25/drivers/gpu/drm/drm_dp_helper.c:3482:19: error: call to undeclared function 'backlight_get_brightness'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
        u16 brightness = backlight_get_brightness(bd);
                         ^
/usr/ports/graphics/drm-515-kmod/work/drm-kmod-drm_v5.15.25/drivers/gpu/drm/drm_dp_helper.c:3482:19: note: did you mean 'backlight_device_set_brightness'?
/usr/src/sys/compat/linuxkpi/common/include/linux/backlight.h:95:1: note: 'backlight_device_set_brightness' declared here
backlight_device_set_brightness(struct backlight_device *bd, int brightness)
^
/usr/ports/graphics/drm-515-kmod/work/drm-kmod-drm_v5.15.25/drivers/gpu/drm/drm_dp_helper.c:3485:7: error: call to undeclared function 'backlight_is_blank'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
        if (!backlight_is_blank(bd)) {
             ^
/usr/ports/graphics/drm-515-kmod/work/drm-kmod-drm_v5.15.25/drivers/gpu/drm/drm_dp_helper.c:3485:7: note: did you mean 'backlight_disable'?
/usr/src/sys/compat/linuxkpi/common/include/linux/backlight.h:114:1: note: 'backlight_disable' declared here
backlight_disable(struct backlight_device *bd)