Thank you, this result is extremely useful. The physical response confirms that VESA AUX is the working brightness-control interface for this screen. In automatic mode the kernel selects PWM based on the firmware information, but that interface changes only the software value and does not affect the physical panel.
The unusual behavior near the top of the slider appears to be a separate range problem. In VESA AUX mode the kernel currently exposes a range of 0 to 512 because it did not obtain the panel's actual maximum luminance. The significant dimming in the final approximately 2% occurs close to values above 500, but I need to verify the limit reported by this exact panel rather than assume that it is 500. Please keep the same RC5 kernel and xe.enable_dpcd_backlight=2 setting, then run: cat /sys/class/drm/card*-eDP-*/edid > ~/edid.bin Please attach the resulting edid.bin file. No additional slider test is needed for now. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2163288 Title: HP ZBook X G1i: JHL7540 xHCI dies when Thunderbolt Dock G2 is connected during boot; hot-plug works To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2163288/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
