Public bug reported: [Impact] Dell XPS 15 9510(TGL) uses DPCD to control backlight, and need to add this panel to edid_quirk.
kernel: [ 1.719773] i915 0000:00:02.0: [drm] Panel advertises DPCD backlight support, but VBT disagrees. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=1. If your machine needs this, please file a _new_ bug report on drm/i915, see https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs for details. Kernel 5.12+ support the backlight via: commit: <4a8d79901d5b> ("drm/i915/dp: Enable Intel's HDR backlight interface (only SDR for now)"), and doesn't need this quirk. [Fix] Adding the panel's MFG to edid_quirk makes system switch to use DPCD to control backlight. [Test] Verified on Dell XPS 9510(TGL) [Where problems could occur] The quirk is for a dedicate panel, and won't affect other platforms. ** Affects: hwe-next Importance: Undecided Status: New ** Affects: linux (Ubuntu) Importance: Undecided Status: Invalid ** Affects: linux-oem-5.10 (Ubuntu) Importance: Undecided Status: Invalid ** Affects: linux (Ubuntu Focal) Importance: Undecided Assignee: AceLan Kao (acelankao) Status: In Progress ** Affects: linux-oem-5.10 (Ubuntu Focal) Importance: Undecided Assignee: AceLan Kao (acelankao) Status: In Progress ** Affects: linux (Ubuntu Groovy) Importance: Undecided Assignee: AceLan Kao (acelankao) Status: In Progress ** Affects: linux (Ubuntu Hirsute) Importance: Undecided Assignee: AceLan Kao (acelankao) Status: In Progress ** Tags: oem-priority originate-from-1933030 somerville ** Also affects: linux (Ubuntu Hirsute) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Groovy) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Focal) Importance: Undecided Status: New ** Also affects: linux-oem-5.10 (Ubuntu) Importance: Undecided Status: New ** Changed in: linux (Ubuntu Focal) Status: New => In Progress ** Changed in: linux (Ubuntu Groovy) Status: New => In Progress ** Changed in: linux (Ubuntu Hirsute) Status: New => In Progress ** Changed in: linux-oem-5.10 (Ubuntu Focal) Status: New => In Progress ** Changed in: linux (Ubuntu) Status: New => Invalid ** Changed in: linux-oem-5.10 (Ubuntu) Status: New => Invalid ** No longer affects: linux-oem-5.10 (Ubuntu Groovy) ** No longer affects: linux-oem-5.10 (Ubuntu Hirsute) ** Changed in: linux (Ubuntu Focal) Assignee: (unassigned) => AceLan Kao (acelankao) ** Changed in: linux (Ubuntu Groovy) Assignee: (unassigned) => AceLan Kao (acelankao) ** Changed in: linux (Ubuntu Hirsute) Assignee: (unassigned) => AceLan Kao (acelankao) ** Changed in: linux-oem-5.10 (Ubuntu Focal) Assignee: (unassigned) => AceLan Kao (acelankao) -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1933566 Title: XPS 9510 (TGL) Screen Brightness could not be changed Status in HWE Next: New Status in linux package in Ubuntu: Invalid Status in linux-oem-5.10 package in Ubuntu: Invalid Status in linux source package in Focal: In Progress Status in linux-oem-5.10 source package in Focal: In Progress Status in linux source package in Groovy: In Progress Status in linux source package in Hirsute: In Progress Bug description: [Impact] Dell XPS 15 9510(TGL) uses DPCD to control backlight, and need to add this panel to edid_quirk. kernel: [ 1.719773] i915 0000:00:02.0: [drm] Panel advertises DPCD backlight support, but VBT disagrees. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=1. If your machine needs this, please file a _new_ bug report on drm/i915, see https://gitlab.freedesktop.org/drm/intel/-/wikis/How-to-file-i915-bugs for details. Kernel 5.12+ support the backlight via: commit: <4a8d79901d5b> ("drm/i915/dp: Enable Intel's HDR backlight interface (only SDR for now)"), and doesn't need this quirk. [Fix] Adding the panel's MFG to edid_quirk makes system switch to use DPCD to control backlight. [Test] Verified on Dell XPS 9510(TGL) [Where problems could occur] The quirk is for a dedicate panel, and won't affect other platforms. To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1933566/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
