An ATTR{}= assignment on the add event races the amdgpu probe (the
power_dpm attribute doesn't exist yet), so it silently no-ops at boot
(observed: level stayed 'auto'). Fire on the bind action — driver bound
and sysfs attrs created — and write via RUN with %p devpath.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014S8VtAvG499SsCbeESRK7V