I got wierd screen blinking after update kernel from 5.8.18-rockchip to 5.9.14-rockchip.

Here is blurry video with screen blinking.

My screen resolution is 1600x900 and i'm using HDMI-to-VGA adapter. All was working fine with kernel 5.8.18-rockchip.

I still can connect to sbc via ssh, so I checked kernel version, install old one and blinking gone:

q@tinkerboard:/var/cache/apt/archives$ uname -a
Linux tinkerboard 5.9.14-rockchip #20.11.3 SMP PREEMPT Fri Dec 11 22:00:29 CET 2020 armv7l armv7l armv7l GNU/Linux
q@tinkerboard:/var/cache/apt/archives$ dpkg-deb -I linux-image-current-rockchip_20.11_armhf.deb
 new Debian package, version 2.0.
 size 27169880 bytes: control archive=50048 bytes.
     403 bytes,    12 lines      control
  194536 bytes,  1942 lines      md5sums
     428 bytes,    15 lines   *  postinst             #!/bin/bash
     299 bytes,    12 lines   *  postrm               #!/bin/bash
     932 bytes,    34 lines   *  preinst              #!/bin/bash
     297 bytes,    12 lines   *  prerm                #!/bin/bash
 Package: linux-image-current-rockchip
 Source: linux-5.8.18-rockchip
 Version: 20.11
 Architecture: armhf
 Maintainer: Igor Pecovnik <igor.pecovnik@****l.com>
 Installed-Size: 80090
 Section: kernel
 Priority: optional
 Homepage: http://www.kernel.org/
 Description: Linux kernel, version 5.8.18-rockchip
  This package contains the Linux kernel, modules and corresponding other
  files, version: 5.8.18-rockchip.
q@tinkerboard:/var/cache/apt/archives$ sudo dpkg -i linux-image-current-rockchip_20.11_armhf.deb
dpkg: warning: downgrading linux-image-current-rockchip from 20.11.3 to 20.11
(Reading database ... 112356 files and directories currently installed.)
Preparing to unpack linux-image-current-rockchip_20.11_armhf.deb ...
update-initramfs: Deleting /boot/initrd.img-5.9.14-rockchip
Removing obsolete file uInitrd-5.9.14-rockchip
Unpacking linux-image-current-rockchip (20.11) over (20.11.3) ...
Setting up linux-image-current-rockchip (20.11) ...
update-initramfs: Generating /boot/initrd.img-5.8.18-rockchip
update-initramfs: Converting to u-boot format
q@tinkerboard:/var/cache/apt/archives$ sudo reboot

Please, fix blinking bug in 5.9.14-rockchip.

Looks like problem raised when hdmi patches was disabled: https://github.com/armbian/build/commit/62c27823a637698e88284bc0c0f0d31342ed9641

Hello, the HDMI timing patches have been disabled. They still compile fine, but for some reason made my very standard full-hd 60Hz monitor unable to work.

Maybe something changed in kernel 5.9 (apparently could not find anything related though) that makes HDMI timing patches work bad.

 

You may try and compile with the patches back on and see if your adapter works again. I have access to more equipment now and can do some more checks if you report that the patches are working good for you.