[Motorola Edge 20 Pro] LSS4181:
UPDATE 3: At least for LOS 20 it seems the fix has been brought back upstream at some point, so this should be FIXED on most recent builds.

On the other hand, a workaround would be to enable Always-on Display (AOD). Since the bug occurs when turning the screen on from off, by keeping the screen on, the bug may be avoided.

REGRESSION WARNING: According to reports the issue has regressed since LOS 20231225. I'm currently on LMO 4.2 (Jan 8 2024) and am yet to reproduce this issue on my device, so I'm holding back further updates. Not sure, but there's a good chance further LMO versions may be affected!

As such, if you're currently on a version that does not have the screen failure issue, DO NOT UPDATE ANY FURTHER!

UPDATE 2: I'm editing the title as I have now considered the issue FIXED. It's been 6 months since then and I haven't seen a single occurrence of screen failure. During the period I've updated the system using LMODroid's updater several times. Everything's fine so far.

UPDATE: A commit that appears to have fixed the issue has been merged and is now available as of LMODroid 20230121. So far no screen failure observed for the past few days. If the issue does not resurface for a long enough period, the issue can be considered fixed. Many thanks to Electimon for the commit.

Originally I posted a series of reports on the unofficial LOS19 thread regarding an infrequent but very annoying issue that the screen may sometimes fail to turn on and require a system reboot to recover.

This affects both Lineage and LMODroid. I'm currently on LMODroid. It keeps USB debugging turned on by default so it's much easier to obtain logcats whenever it happens.

Here are something I've found:

1. The screen can die under any circumstance with the error having a chance to happen every time the screen turns on. Fingerprint sensor, as well as other aspects such as HBM, have been ruled out as possible causes, since the issue can be reproduced under situations not involving them at all.

2. Whenever it happens, the "dsi-ctrl-0: Command transfer failed" error would repeat exactly 72 times. The logcat does not explain what exactly these 72 commands are, however.

3. In some builds, a DSI PLL(0) lock failure error would be the first to appear, like in this one, while in other builds, that error would not show up and the first error message would be the command transfer failure. The rest of the error messages remain identical from what I could see.

4. Previously, from the logcat, the phone would try to re-initialize the panel twice (which always failed), before giving up and ignoring any further bl_level changes. However, as of this build (LMODroid 20230107), the situation changed. I've noticed some additional DSI-related log entries, that were not present from logcats captured from previous builds, and it seems to be trying to re-initialize the panel a few more times than before.

Here's a recent logcat I got from the LMODroid 20230107 build, filtered by the keyword "dsi". The issue has been ongoing since at least 20221201 when I first started using it. I added a separator before lines that are new to the 20230107 build.

Spoiler content hidden.

Additionally, this particular error message seems to indicate some issue with the regulator, but I'm not entirely sure. This error message was not present in logcats from previous builds.

01-11 08:11:06.535 0 0 E : [drm:dsi_pwr_enable_regulator] *ERROR* [msm-dsi-error]: Unbalanced regulator off:vddio

I'm not an expert, so I've no idea about this regulator (vddio) error but these new messages might lead to something closer to the root cause of the issue.