Updated the description with the SRU template. ** Description changed:
+ [Impact] + + Plymouth draws the splash separately on every DRM display controller. A + tiled monitor is one panel driven through several controllers, described + by the connector TILE property, so plymouth draws a full splash on each + tile. + + On a Dell UP3218K (7680x4320, two tiles) boot and shutdown show two + logos and two spinners side by side instead of one. This affects all + 26.04 LTS users with tiled monitors. + + [Fix] + + Cherry-pick seven commits from upstream main (not yet released). All + apply unmodified. + + 43b66bfe drm: guard gamma ramp setup against bogus gamma_size + d06b757a drm: Parse tiled display metadata + dd685898 drm: Select modes for display tiles + dd677c87 drm: Plan tiled display geometry + 94cb2c8c drm: Store scanout state per controller + b3342873 drm: Read connector tile properties + 12309506 drm: Combine tiled outputs into logical heads + + The last six are MR !496. 43b66bfe (MR !411) is a prerequisite for + 94cb2c8c. The MR's three test-only commits are left out: they extend + upstream's unit-test suite, which is newer than the packaged snapshot, + and they don't change the shipped binaries. + + [Test Plan] + + On 26.04 with a Dell UP3218K connected by both DisplayPort cables, + booted with plymouth.debug: + + 1. With -0ubuntu8: two logos and two spinners at boot and shutdown. + 2. With the update: one logo and one spinner, centred, at boot and + shutdown. /var/log/plymouth-debug.log contains "Creating 7680x4320 + logical head for TILE group". + + Regression checks, which should look the same as with -0ubuntu8: + - laptop panel only + - laptop panel plus a non-tiled external monitor + - full-disk encryption passphrase prompt + - a VM (e.g. QEMU with virtio-gpu) + + [Where problems could occur] + + Plymouth runs in the initramfs and at shutdown, and shows the + disk-encryption passphrase prompt, so regressions would appear at boot + or shutdown. + + * 94cb2c8c changes how every display is driven, not only tiled ones. A + mistake could mean a missing or misplaced splash, a black screen, or + plymouthd crashing. The worst case is an encrypted-disk user who + cannot see the passphrase prompt. + * The tiled path only runs for connectors with a TILE property, and + incomplete or inconsistent tile groups fall back to the old + behaviour. A wrong decision would show as a stretched, cropped or + still duplicated splash on a tiled monitor. + * 12309506 recalculates the panel size used to place the firmware + (BGRT) logo, which could move it on multi-display systems. + + [Other Info] + + * Upstream issue: https://gitlab.freedesktop.org/plymouth/plymouth/-/issues/353 + * MRs: https://gitlab.freedesktop.org/plymouth/plymouth/-/merge_requests/496 + https://gitlab.freedesktop.org/plymouth/plymouth/-/merge_requests/411 + * The same code, built in PPA ~kchsieh/verification, was tested on 26.04 + with a UP3218K (comment #2). + + --- Original description --- + The DRM renderer currently creates a separate head for every active display controller. A tiled monitor exposes several controllers for segments of the same physical panel, so Plymouth lays out the splash independently on each segment. On displays such as the Dell UP3218K, that behavior produces two logos and two progress indicators across one 7680x4320 monitor. DRM already provides the group, grid position, and tile dimensions needed to identify the physical layout. This has been fixed upstream here: https://gitlab.freedesktop.org/plymouth/plymouth/-/commit/a2ef9b02a1aa1a43c9234097af60097ae5bf6498 This should be brought into Ubuntu to increase tiled display compatibility ** Also affects: oem-priority Importance: Undecided Status: New ** Tags added: oem-priority ** Tags added: jira-somerville-5491 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2167376 Title: Plymouth doesn't handle tiled displays properly To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/2167376/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
