Bug 2339072

Summary: Plymouth shows black screen before FDE password prompt when setting plymouth.use-simpledrm on Nvidia Optimus system
Product: [Fedora] Fedora Reporter: Mateus Rodrigues Costa <mateusrodcosta>
Component: plymouthAssignee: Ray Strode [halfline] <rstrode>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 41CC: gnome-sig, hdegoede, pedrohqb, r9290x, rstrode
Target Milestone: ---   
Target Release: ---   
Hardware: Unspecified   
OS: Linux   
Whiteboard:
Fixed In Version: plymouth-24.004.60-19.fc43 plymouth-24.004.60-19.fc42 Doc Type: ---
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Last Closed: 2025-07-03 22:20:36 UTC Type: ---
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Description Flags
Plymouth debug logs none

Description Mateus Rodrigues Costa 2025-01-20 22:59:18 UTC 
One of the recent proposed changes for Fedora 42 is https://fedoraproject.org/wiki/Changes/PlymouthUseSimpledrm, which switches the driver used for plymouth from the actual GPU's driver to simpledrm. One reason this is planned is because some big drivers (such as AMD's) might time out.

However there's is a chance that this change causes a black screen during some part of the boot due to the switch from simpledrm to the actual GPU driver.

As per the thread on https://gitlab.freedesktop.org/plymouth/plymouth/-/issues/264#note_2744540 I was suggested to get debug logs from plymouth to report.

The system is a Dell G5 5590 running Fedora Silverblue 41.
It is a Nvidia Optimus system with a Intel UHD Graphics 630 as the iGPU and a NVIDIA GeForce GTX 1660 Ti (using the proprietary driver) as the dGPU.

It is a UEFI system which is running the latest BIOS update (1.27.0) and Secure boot is enabled.

Kernel parameters are:

```
$ rpm-ostree kargs
rd.luks.uuid=luks-<snip> rhgb quiet root=UUID=<snip> rootflags=subvol=root,compress-force=zstd:6 rw rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 intel_iommu=on nosgx mem_sleep_default=deep plymouth.use-simpledrm log_buf_len=50M plymouth.debug=stream:/dev/null ostree=<snip>
``` 

Reproducible: Always

Steps to Reproduce:
1. Add `plymouth.use-simpledrm` to the boot arguments
2. Reboot and check the plymouth boot
Actual Results:  
Black screen before FDE password prompt

Expected Results:  
Flicker-free boot
Comment 1 Mateus Rodrigues Costa 2025-01-20 23:00:06 UTC 
Created attachment 2066838 [details]
Plymouth debug logs
Comment 2 Pedro Barreto 2025-04-07 02:24:26 UTC 
I confirm the bug here also running Fedora 42 Silverblue. I have a dual GPU set: a) as a iGPU I have a Intel® UHD Graphics 770 (ADL-S GT1) - which I usually use; b) as a dGPU, I have a AMD Radeon™ Pro W6400.
Comment 3 Pedro Barreto 2025-04-07 02:58:32 UTC 
My Silverblue's commit is d93ae80aec6b8db79f59cf6a0d77c9db19190a7083dc4984351171bf85442f29
Comment 4 Hans de Goede 2025-04-07 07:59:57 UTC 
Thank you for your bug report.

Likely your boot was not truely flickerfree before the https://fedoraproject.org/wiki/Changes/PlymouthUseSimpledrm change. What has changed is that before the modeset would happen (and the screen would go black) before the disk-unlock screen shows and now the disk-unlock screen shows earlier (as intended) and then the modeset happens while it is showing causing the screen to go black.

You can verify this by disabling the use of simpledrm in plymouth, see: https://fedoraproject.org/wiki/Changes/PlymouthUseSimpledrm#Release_Notes and then closely look at the screen when booting. What should happen is that the display goes from showing the vendor logo to the disk-unlock screen without turning black in between. What I expect will happen instead is that it turns black for the same amount of time as you now notice because the turning black now happens while the disk-unlock screen is already showing.

I assume that your internal laptop LCD panel is connected to the Intel iGPU, if it were connected to the nvidia GPU then this would not happen since the nvidia binary driver should not be in the initrd at all. The real problem here is that the so called fastmodeset the i915 driver is supposed to do at boot is broken and instead it is falling back to a slow full modeset. This has been broken for a while now on many different laptop models. I would love to look into this and fix the i915 driver (this has broken in the past and I've fixed it before) but unfortunately I do not have time to work on fixing the fastmodeset support in the i915 driver.
Comment 5 Hasshu 2025-06-21 10:34:58 UTC 
I seem to be experiencing this very issue on F42 Workstation. RX 6650 XT (amdgpu) and no integrated graphics here.
Comment 6 Hans de Goede 2025-07-01 21:31:43 UTC 
This should be fixed by this upstream merge-request:

https://gitlab.freedesktop.org/plymouth/plymouth/-/merge_requests/355

I'm working on preparing a plymouth update addressing several issues including this one.
Comment 7 Fedora Update System 2025-07-03 20:54:10 UTC 
FEDORA-2025-bea98bd9ab (plymouth-24.004.60-19.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2025-bea98bd9ab
Comment 8 Fedora Update System 2025-07-03 22:20:36 UTC 
FEDORA-2025-bea98bd9ab (plymouth-24.004.60-19.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.
Comment 9 Fedora Update System 2025-07-04 09:00:56 UTC 
FEDORA-2025-84de48bce5 (plymouth-24.004.60-19.fc42) has been submitted as an update to Fedora 42.
https://bodhi.fedoraproject.org/updates/FEDORA-2025-84de48bce5
Comment 10 Fedora Update System 2025-07-05 15:47:04 UTC 
FEDORA-2025-84de48bce5 has been pushed to the Fedora 42 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2025-84de48bce5`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2025-84de48bce5

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
Comment 11 Fedora Update System 2025-07-07 00:50:08 UTC 
FEDORA-2025-84de48bce5 (plymouth-24.004.60-19.fc42) has been pushed to the Fedora 42 stable repository.
If problem still persists, please make note of it in this bug report.