Fairphone 4: Display most of the time does not work (happens on v24.06 and edge)

Describe your issue

What's the expected behaviour?

I expect the display to display the mobile desktop UI.

What's the current behaviour?

The background light is on but the screen is black. The display works by hitting the power key several times (i.e. switch the display on and off and then it works eventually)

How to reproduce your issue?

Create a fresh Phosh or Plasma Mobile installation and boot into it. The display initially shows command line output and then goes black. With Phosh it can be quickly reactivated by switching the display on and off several times and on Plasma Mobile it takes a bit longer because the display cannot be switched off manually - one has to wait a minute or so until it switches off automatically (it gets better after the first login).

In my last test, on Phosh, I had to switch it on and off exactly 5 times but I think this is not a rule.

What device are you using?

fairphone-fp4

On what postmarketOS version did you encounter the issue?

• edge (master branch)

• v24.06

• v23.12 (supported until 2024-07-16)

• I confirm that the issue still is present after running sudo apk upgrade -a

On what environment did you encounter the issue?

Environments

• GNOME Shell on Mobile
• Phosh
• Plasma Mobile
• Sxmo (Wayland/Sway) Please post the output of sxmo_version.sh
• Other: Please fill out

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in yyyy-mm-dd format)

I am unsure

Additional information

The output of dmesg:

changed the description

By Apollo3zehn on 2024-07-01T06:50:22

assigned to @z3ntu

By Newbyte on 2024-07-01T10:09:03

added device-fairphone-fp4 status::reported type::bug labels

I'm aware of a variation of this bug for a while, but it's surprising right now that with pmaports kernel (6.9.7 from !5290 (merged)) that is takes either 4 or 5 times reliably to get the screen to display something again.

With my development branch (6.10-rc5) it's off (broken) during bootup but after toggling it once it starts working and keeps working reliably.

At some point I've debugged this to a power domain needing to be turned off and if I force that one on it never starts working. But I haven't been able to figure out the deeper reasons or how to properly fix it... :(

By Luca Weiss on 2024-07-07T20:05:48

Right now, while trying to test merge request !5321 (merged), the error messages changed a bit:

But if that is gone (or much different) with 6.10 there is probably no use in investigating it further for 6.9.x.

By Apollo3zehn on 2024-07-07T20:05:48

All these messages (apart from dsi_err_worker one) are unrelated to display but only to touchscreen, and the display problem also happens without touchscreen driver even being loaded. The touchscreen just loses power when the screen goes off so then of course communication stops working also.

On Friday I spent some more time trying to dig down how the screen problem happens. I could only reproduce it in the "only works every 4-5 times" variant only when built with config from pmaports and all the loadable modules loaded. So far everything I see points to some sort of timing issue or race condition somewhere but I really haven't been able to pinpoint anything yet...

By Luca Weiss on 2024-07-07T21:21:58

mentioned in merge request !5602 (merged)

By Apollo3zehn on 2024-10-04T19:23:11

M/R !5602 (merged) solves this issue :-)

By Apollo3zehn on 2024-10-04T19:24:18

closed

Still don't know what it is but apparently doing DRM_MSM=y makes it quite a bit better. And when booting the screen will be off the first time, but at least after it seems to consistently turn on again... Fun issue :)

By Luca Weiss on 2024-10-04T20:22:09

mentioned in commit 6bdf4509

By Luca Weiss on 2024-10-04T21:19:42