The eDP panel in the Lenovo Yoga 9 2-in-1 14IPH11 declares its luminance range only in the DisplayID 2.0 Display Parameters block, with no CTA extension at all. The core ignores those fields, so i915 refuses the Intel HDR backlight interface and falls back to PWM, which drives nothing on this OLED panel: brightness cannot be changed at all.
Patch 1 reads the range in the core, patch 2 lets i915 use it whatever its source. Patch 2 depends on patch 1, so the series should go through one tree. Based on drm-misc-next. Cristian La Spina (2): drm/edid: read the luminance range from DisplayID 2.0 drm/i915/display: accept a luminance range from any source drivers/gpu/drm/drm_edid.c | 47 +++++++++++++++++++ .../drm/i915/display/intel_dp_aux_backlight.c | 17 ++++--- include/drm/drm_connector.h | 3 +- 3 files changed, 57 insertions(+), 10 deletions(-) -- 2.52.0
