I had a look at building a kernel with various parts of this change list. I found one that is causing the backlight problems I see. This commit breaks backlight setting on a Samsung 940X with i5-3317U cpu-
- drm/i915/backlight: Remove try_vesa_interface https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=40d2f5820951dee818d05c14677277048bd85f9f The previous version of intel_dp_aux_init_backlight_funcs in drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c had a display->params.enable_dpcd_backlight case of INTEL_DP_AUX_BACKLIGHT_AUTO which would only try VESA interface for a panel->vbt.backlight.type of INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE or INTEL_BACKLIGHT_DISPLAY_DDI or "if (intel_dp->edp_dpcd[0] >= DP_EDP_15)" The new version of intel_dp_aux_init_backlight_funcs tries a VESA interface for all values of panel->vbt.backlight.type including INTEL_BACKLIGHT_PMIC or INTEL_BACKLIGHT_LPSS or INTEL_BACKLIGHT_DSI_DCS or INTEL_BACKLIGHT_PANEL_DRIVER_INTERFACE even when "(intel_dp->edp_dpcd[0] < DP_EDP_15)". That is overriding funcs that are set in drivers/gpu/drm/i915/display/intel_backlight.c by intel_backlight_init_funcs before it calls intel_dp_aux_init_backlight_funcs. Perhaps there is a case for the TUXEDO devices that is more selective and will avoid breaking others. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2152570 Title: Patchset for TUXEDO devices To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2152570/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
