Launchpad has imported 6 comments from the remote bug at https://bugzilla.kernel.org/show_bug.cgi?id=205699.
If you reply to an imported comment from within Launchpad, your comment will be sent to the remote bug automatically. Read more about Launchpad's inter-bugtracker facilities at https://help.launchpad.net/InterBugTracking. ------------------------------------------------------------------------ On 2019-11-29T02:13:49+00:00 sda wrote: Created attachment 286111 fix_max_backlight_calculations When running Ubuntu with linux-image-5.3.0-23-generic, mainline 5.3.13, or latest 5.4+ my Lenovo ThinkPad P1 Gen 2 is unable to change the backlight brightness. The buttons trigger the on-screen display and move the bar but the actual display brightness does not change. With the kernel option i915.enable_dpcd_backlight=1 it does make the backlight change but erratically. For example moving through the range you get stuff like off, medium bright, dim, bright, medium, off. This does work in Ubuntu linux-image-4.15.0-1059-oem. It seems the following commits in particular make the difference. UBUNTU: SAUCE: i915: intel_dp_aux_backlight: Fix max backlight calculations https://git.launchpad.net/~canonical-kernel/ubuntu/+source/linux-oem/+git/eoan/commit/?h=oem&id=ff39163c455f31005e2709a2006a7605b3d8a05f UBUNTU: SAUCE: drm/i915: customize DPCD brightness control for specific panel https://git.launchpad.net/~canonical-kernel/ubuntu/+source/linux-oem/+git/eoan/commit/?h=oem&id=cf7286b44a6e27967f5ed134c4492dd17bde118a I ported the above commits to the latest linux mainline kernel and am running that. This was in part because >= 5.3.12 fixes another issue with this hardware where the screen remains black after a resume (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854177). https://github.com/altendky/linux/commit/395eb4b85f6a0f85061c0598247727de0d9316f6 https://github.com/altendky/linux/commit/c2dc38e6aadf3d979bea83e382a1b119574df7af Built with: git clean -fdx && cp /boot/config-5.3.0-23-generic .config && yes '' | make oldconfig && make clean && make -j `getconf _NPROCESSORS_ONLN` deb- pkg LOCALVERSION=-altendky-backlight Note that the use of DEVICE_ID_ANY is likely bad and the correct ID for this panel should be identified. I wanted to first confirm it worked before bothering to figure out which ID was needed there and how to get it. Reply at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854413/comments/0 ------------------------------------------------------------------------ On 2019-11-29T02:14:31+00:00 sda wrote: Created attachment 286113 customize_dpcd_brightness_control_for_specific_panel Reply at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854413/comments/1 ------------------------------------------------------------------------ On 2019-11-29T02:16:14+00:00 sda wrote: Created attachment 286115 fix_max_backlight_calculations Reply at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854413/comments/2 ------------------------------------------------------------------------ On 2019-11-29T02:18:27+00:00 sda wrote: I should note that I have naively ported these patches. While I have done embedded C for years and some hardware design... I am not familiar with Linux kernel development nor any details of controlling this hardware. Reply at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854413/comments/3 ------------------------------------------------------------------------ On 2019-11-29T02:28:22+00:00 sda wrote: :[ Also, this laptop has the Samsung OLED panel. Reply at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854413/comments/4 ------------------------------------------------------------------------ On 2019-12-02T11:29:29+00:00 jani.nikula wrote: https://gitlab.freedesktop.org/drm/intel/issues/510 Reply at: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1854413/comments/8 ** Changed in: linux Importance: Unknown => Medium ** Bug watch added: gitlab.freedesktop.org/drm/intel/issues #510 https://gitlab.freedesktop.org/drm/intel/issues/510 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1854413 Title: Backlight adjustments shows OSD but does not change anything on Samsung OLED panel To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1854413/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
