no video signal (dpms off?) during plymouth on AMD Radeon HD 4200 Series integrated

[Stephen Warren]

I'm running Quantal, with the following HW:

00:00.0 Host bridge: Advanced Micro Devices [AMD] RS880 Host Bridge
...
01:05.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI RS880 [Radeon HD 4290]

When I boot, I see the BIOS screen, then grub (I've commented out GRUB_HIDDEN_TIMEOUT in /etc/default/grub so that grub shows, although this makes no difference to this bug; it happens either way), then as soon as the kernel and/or plymouth starts, the monitor turns off and says "no signal".

If I edit /etc/defaultgrub and remove "quiet splash" from GRUB_CMDLINE_LINUX_DEFAULT, then this does not happen - I see kernel log messages just fine. I also tried just "splash", and the problems does show up there. So, the variable here is whether plymouth ("splash") runs or not, hence I'm filing this against plymouth rather than the kernel initially.

I also have a cryptoroot, so when I boot the system plymouth stops and prompts me for the password. And, I've install busybox and dropbear, so I can ssh into the cryptoroot. If I do so, then run "chvt 1" the display comes back. Then, running "chvt 7" shows the expected plymouth screen.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.