Dell XPS 13 9310 Vpro panel advertises DPCD backlight support, but VBT disagrees
Can't use intel_backlight node to control built-on panel backlight.
The kernel report: kernel: i915 0000:00:02.0: [drm:intel_dp_aux_init_backlight_funcs [i915]] Panel advertises DPCD backlight support, but VBT disagrees. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=1. If your machine needs this, please file a new bug report on drm/i915, see https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs for details.
Seems the VBT doesn't config correctly.backlight.logi915_vbt
The kernel log and /sys/kernel/debug/dri/0/i915_vbt are attached.