port-arm/54342: Pinebook screen glitches/offsets on top and extreme right of the screen with modeset enabled

[leot%NetBSD.org@localhost]

>Number:         54342
>Category:       port-arm
>Synopsis:       Pinebook screen glitches/offsets on top and extreme right of the screen with modeset enabled
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-arm-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 04 09:05:00 +0000 2019
>Originator:     Leonardo Taccari
>Release:        NetBSD 8.99.49
>Organization:
Università Politecnica delle Marche
>Environment:
System: GENERIC64 NetBSD 8.99.49 of 12:00 UTC Jul 2 2019
Architecture: aarch64
Machine: evbarm
>Description:
	On 14" Pinebook model when booting with `modeset' (default) enabled
	there are screen glitches/wrong offsets on the top of the screen and
	extreme right.  ASCII art trying to illustrate the problem:

	 +---------------------------------------+
	 |=======================================|<- unexpected "violet" bar
	 |[                                     ||\
	 |[                                     || \
	 |[                                     ||  | the first `[' character
	 |[                                     ||  | of dmesg timestamp can
	 |[                                     ||  | be seen on the extreme
	 |[                                     ||  | right too
	 |[                                     || /
	 |[                                     ||/
	 |_                                     _|<- part of the input cursor
	 +---------------------------------------+   can be seen on the
						     extreme right

	...and here the corresponding photograph of the problem:
	 
	 <https://www.NetBSD.org/~leot/tmp/pinebook-modeset-screen_problems.jpg>
>How-To-Repeat:
	Boot a GENERIC64 kernel on a 14" Pinebook.
>Fix:
	No idea, sorry!

	A possible workaround to that problem is to boot the kernel with
	`nomodeset', e.g. on the EFI prompt:

	 > boot netbsd nomodeset