T420s white screen

[Jason Andryuk]

Hi,

I've been running coreboot on my T420s for a year or so.  It was
working fine, but today it isn't booting.  When I hit the power
button, I just get a white screen.  Well, maybe grey and not white,
but not the black background with white text like I usually see for my
seabios payload.

I tried blindly booting and getting past the disk encryption, but I
didn't see the laptop DHCP to the router.  I might have botched that
though...

Once or twice earlier I had this white screen.  In those cases, I just
powered off and tried again and it worked.

Has anyone seen something like this before?

One thought is the RTC battery may be old and have lost its charge.
But would a dead battery exhibit this behavior?

Thanks,
Jason

[Jason Andryuk]

On Thu, May 21, 2020 at 1:41 PM Jason Andryuk  wrote:
> Hi,
>
> I've been running coreboot on my T420s for a year or so.  It was
> working fine, but today it isn't booting.  When I hit the power
> button, I just get a white screen.  Well, maybe grey and not white,
> but not the black background with white text like I usually see for my
> seabios payload.
>
> I tried blindly booting and getting past the disk encryption, but I
> didn't see the laptop DHCP to the router.  I might have botched that
> though...

Oh, I also had to login for NetworkManager to connect to the wifi, which it did.

I shut the lid and it went to sleep.  Upon reopening, the screen came
back black with the backlight on.  I don't usually put it to sleep, so
failing to resume the display may what normally happens.

I hard powered off.  When I powered back on, the seabios text was present.

-Jason

[Jonathan Neuschäfer]

On Thu, May 21, 2020 at 01:41:30PM -0400, Jason Andryuk wrote:
> Has anyone seen something like this before?

I had white screens on my old laptop (DELL Latitude E6400) whenever the
LVDS cable slipped out of the display panel.

One thing you could try in order to see what's going on is to boot with
an external monitor connected.

greetings,
Jonathan

[Jason Andryuk]

On Fri, May 22, 2020 at 3:16 AM Jonathan Neuschäfer
 wrote:
> On Thu, May 21, 2020 at 01:41:30PM -0400, Jason Andryuk wrote:
> > Has anyone seen something like this before?
>
> I had white screens on my old laptop (DELL Latitude E6400) whenever the
> LVDS cable slipped out of the display panel.

Hmmm, yes I suppose that could have happened.  It's worth checking at
least.  Thanks for the idea.  Unfortunately, the laptop requires more
disassembly then I'd like to get to the back connector.
> One thing you could try in order to see what's going on is to boot with
> an external monitor connected.

Last night the machine reverted to the white screen booting.  This
morning, with an external monitor attached, there was a white screen
flash and then it went to black with the seabios text.  I only booted
once, so I haven't investigated further.

Thanks,
Jason