Re: HEADS UP: Merging drm update (Lenovo X230 mode switch issue in UEFI mode only, BIOS works)

[Matthias Petermann <mp%petermann-it.de@localhost>]

Hello,

first of all, thanks for the effort to bring an up-to-date DRM to 
NetBSD! Proper graphics support is essential for most users and 
therefore the work cannot be appreciated enough.

I have now also managed to test current on my laptop and made an 
observation that I would like to share and hopefully be able to help to 
clarify / fix the underlying issue.

The Laptop is a Lenovo X230 model with i5 CPU and integrated intel 
graphics. It can boot NetBSD in both - BIOS (CSM) and UEFI mode.

- With NetBSD 9.2, the mode switch (when initializing the i915drmkms0 
device) works fine in both boot modes.

- In current from 28.12.2021 the mode switch only works when I boot in 
BIOS mode.

- When I boot current in UEFI mode, after the mode switch it only 
displays a blank screen with a white background. After that, within a 
few seconds, a kind of randomly structured dark spot develops from the 
center of the screen, which then stretches to the edge of the screen [1].

One (not necessarily related) observation: after the appearance of the 
above-mentioned spot, I turn off the laptop and boot back into NetBSD 
9.2. Immediately afterwards, I have a strange flickering on the display, 
which is especially noticeable with brighter colors. The graphical 
display seems normal otherwise. The flickering then disappeared again 
over time. Although I have absolutely no idea about it, my first thought 
was that the dark spot could be some kind of thermal problem that occurs 
with the mode switch? Is this possible?

In any case, I would like to help track down the problem. I'm building a 
current from the current sources and then setting up an identical laptop 
as a test machine. In the meantime, I'd appreciate any hints on what 
might be needed as diagnostic data.

Many greetings
Matthias

[1] http://www.petermann-it.de/netbsd/netbsd-drm.mp4
(SSL certicate renewal in progress)