Display blank on Raspberry Pi OS Bullseye

[shbisson]

Describe the bug

Display blank on Raspberry Pi OS Bullseye. Flashes during reboot and then stays blank. Could be an issue with the new KMS display drivers?

To Reproduce

Install using online installer on Bullseye, reboot.

Your HyperPixel 4

Square touch 2021

Your Raspberry Pi

1. Raspberry Pi 4 4GB Revision: c03114
2. Description: Raspbian GNU/Linux 11 (bullseye) 5.10.63-v7l+
3. Fresh install

$ i2cdetect -y 22
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

[shbisson]

Going back to Buster fixed things, so there's clearly some incompatabilty there! Will wait for updated drivers before I attempt the update again...

[Gadgetoid]

Seeing a similar issue on the Pi Zero 2 W. 😬 Looking into it.

[shbisson]

It seems to install on i2c 22 not 7; I wonder if this might be the reason?

[Gadgetoid]

Commenting out dtoverlay=vc4-kms-v3d seems to work reliably for me. I'd say it's definitely something up with the display driver.

Touch is working for me (Bullseye, Pi Zero 2 W) after some tweaks. For some reason gpio-backlight was stealing the touch pins.

The display is working with dtoverlay=vc4-kms-v3d and I see stuff during startup, but the X server just doesn't want to achknowledge it.

Looks like the change from vc4-fkms-v3d to vc4-kms-v3d will also break the rotation support check in hyperpixel4-rotate.

[mickeyvanolst]

@Gadgetoid are you also able to get it working with openGL enabled? I can get it running with your instructions, but not when openGL is enabled in the config.

[Gadgetoid]

@Gadgetoid are you also able to get it working with openGL enabled? I can get it running with your instructions, but not when openGL is enabled in the config.

Nope, enabling openGL loads that overlay I think?

You can try adding: dtoverlay=vc4-kms-dpi-at056tn53v1 to /boot/config.txt which has a close approximation of some new device tree settings I need to supply for things to work properly with kms enabled.

This seems to work but (and this is a big but) rotation seems to be broken, split output between HyperPixel4 + HDMI is not supported and the HyperPixel rotate script will also not work (well it will break things if you use it in --xorg mode).

On the up side, touch input seems to have grown up a lot. It appears to detect touches as touches (hiding the cursor) rather than ponderously poking the curser around.

[mickeyvanolst]

Using dtoverlay=vc4-kms-dpi-at056tn53v1 for me just generates a blank screen after bootup. (RPi Zero W 2)

[rschu68]

Same with me: Commenting out dtoverlay=vc4-kms-v3d works for Pi3-2835
? not tested before going into production maybe

[Gadgetoid]

Yeah it looks like the fix for this is a protracted adventure into figuring out how the heck DPI panels are now supposed to work with KMS.

Basically it's a non-starter for most users until panel timings are upstreamed into https://github.com/raspberrypi/linux/blob/rpi-5.10.y/drivers/gpu/drm/panel/panel-simple.c and available in a Raspberry Pi OS kernel/modules release.

In the short term I may be able to write our own driver installable with DKMS (Dynamic kernel module support) but that's a horrible nightmare for Pi users since it requires the sprawling kernel-headers package is installed which is painful on an SD card.

I'm going to need a bottle of gin.

As for why we're just now finding out about this: nobody tells me anything, and I'm too busy spinning plates to take proactive deep-dives into whatever eldritch horror Linux upstream are cooking up.

[rschu68]

No worries .. the work you do for the community is verry much appriciated!

Grz
~remke

[mickeyvanolst]

@Gadgetoid do you have a url to the latest Raspberry OS image that you fully support?

[shbisson]

After a rebuild I am running happily on downloads.raspberrypi.org/raspios_armhf/images/raspios_armhf-2021-05-28/; which is the latest Buster image on the Raspberry Pi site.

[shbisson]

@Gadgetoid Thanks for your work on this!