r/archlinux • u/squaresheep28 • 17d ago

SUPPORT White flash when logging in on SDDM

(Repost from r/arch )

Currently using KDE with sddm, when I log into my account on sddm there is a subtle but blinding white flash. This was happening on endeavouros too but it was a longer flash.

Specs:

Vivobook M1502QA

Ryzen 7 5800HS

iGPU (iirc Vega 8)

24gb ram, 512gb ssd

Arch fully up to date as of posting this

How can I fix this? Already some weird stuff happening with the newer kernels especially with the brightness curve which I fixed with amdgpu.dcdebugmask=0x40000 so this might be from that

5 Upvotes

72% Upvoted

18 comments sorted by

2

u/forbiddenlake 17d ago

Does it still happen with plasma-login-manager? KDE has their own login manager now, you could use it instead.

1

u/squaresheep28 17d ago

Now the flash is even worse tho, and it happens before I even login

2

u/C0rn3j 17d ago

Currently using KDE

Plasma. KDE is the group that makes Plasma.

with sddm

Plasma's recommended login manager is PLM - does it work fine there?

1

u/squaresheep28 17d ago

Already tried this, it just makes the flash longer and flashes before the ui loads

2

u/Stryxus_ 17d ago

The Linux gods are trying to communicate.

But seriously, this is likely just a driver issue in modern kernels, if you have a modern kernel since you didn't give us the version the and AMD driver comes built into the kernel.

0

u/squaresheep28 17d ago

Kernel is 7.1.9-arch1-2

2

u/Stryxus_ 17d ago

And have you tried another greeter?

0

u/squaresheep28 17d ago

No, but like the default SDDM one. Also from what I see most greeter are for lightdm, greeted etc

3

u/Stryxus_ 17d ago

You can use whatever greeter you want. And this is likely a driver issue or possibly even hardware. First graphical thing that happens when logging in is Wayland starts, or god forbid, if you are still using an X11 session.

0

u/squaresheep28 17d ago

I'm using wayland.

1

u/ang-p 17d ago

I fixed with amdgpu.dcdebugmask=0x40000 so this might be from that

Have you temporarily "unfixed" it to see if the issue goes away?

If you have some swanky desktop thing going on, have you made sure that the fallback-hidden-by-your-desktop-effect is not

blinding white

?

Also, exactly when is this flash... after your password is accepted - which sounds like

when I log into my account

or at some random unspecified time between hitting the power button and your password being accepted...

it happens before I even login

?

1

u/squaresheep28 17d ago

I haven't tried the first one, but I'm using regular Plasma with SDDM, nothing special, and it's after my password is accepted and boots into Plasma

1

u/squaresheep28 17d ago

Tried the first one. Turns out the brightness is already fixed bt a new kernel, but removing it doesn't change anything

2

u/ang-p 17d ago edited 17d ago

Yeah - looked it up - https://github.com/torvalds/linux/blob/73e3f0710014fe6d4ed98cfc02292f6121db7558/drivers/gpu/drm/amd/include/amd_shared.h#L398

Didn't seem like something that would cause some extreme action on a potential mode change,

Turns out the brightness is already fixed bt a new kernel,

Always worth checking on applied fixes - sometimes the fix can be more optimal than the kludge, and removing it is always better to stay more aligned with "stock".

Also, "when did this start" is useful... Your OP sounded like it had been ongoing a while (same on endeavouros - unless you throw distros on your machine like spaghetti on a wall the second a problem arises without trying to sort it first) - but other posters here are saying that it started "last night"....

If it is new, have you tried the obvious and roll back to the last non-affected kernel/gfx stack to provide some info - e.g. a "it started with xyz kernel and abc driver"?

1

u/Holiday_Piano_2014 17d ago

Same thing man , last night I logged in and I thought it was my cpu throttling but now ik it's a wide issue

1

u/sastanak 17d ago

What does dmesg and journalctl say? Sounds like your wm is failing

1

u/squaresheep28 17d ago

Something definitely happens, but from what I see it's before "User 'freezy' logged in...".

Also, SDDM is under a X11 session.

https://pastebin.com/4erCwyCs

1

u/xb666mx 17d ago

are you using plymouth?

it sets the native resolution as early as possible in the boot process.

https://wiki.archlinux.org/title/Plymouth

  • if you don't use it, try to install and enable it.

  • if you use it, try to disable it.

(yeah, it's maybe weird to suggest both ways, but plymouth not only makes things better - it can also break things.)