Bug#1001409: Add privacy screen modules to the initrd
Package: initramfs-tools
Starting with kernel 5.17 the kernel supports the builtin privacy screens built into the LCD panel of some new laptop models.
This means that the drm drivers will now return -EPROBE_DEFER from their probe() method on models with a builtin privacy screen when the privacy screen provider driver has not been loaded yet.
To avoid any regressions Debian should modify its initrd generation tool to include privacy screen provider drivers in the initrd (at least on systems with a privacy screen), before 5.17 kernels start showing up in the Debian repos.
If this change is not made, then users using a graphical bootsplash (plymouth) will get an extra boot-delay of up to 8 seconds (DeviceTimeout in plymouthd.defaults) before plymouth will show and when using disk-encryption where the LUKS password is requested from the initrd, the system may fallback to text-mode after these 8 seconds.
I've written a patch with the necessary changes for dracut, which might be useful as an example for how to deal with this, see: https://github.com/dracutdevs/dracut/pull/1666
ATM the only kms driver using privacy screens is the i915 driver and the only provider is the thinkpad_acpi driver. But both are likely to change (and change soon!), so the detection really should be made dynamic as has been done in the dracut patch.
Note I've also filed a bug for this for Ubuntu in launchpad:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1954320
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