issue with Radeon - total garbage on screen

[Riccardo Mottola <riccardo.mottola%libero.it@localhost>]

Hi!

on my HP genuine AMD laptop, I always had issues with the Radeon 
displaying garbage. It happened with 9.0, 9.99 kernels and also now with 9.1
What changed is that today I was logged in remotely and could check 
"dmesg" and see this:
[ 19618.256460] warning: 
/usr/src/sys/external/bsd/drm2/dist/drm/radeon/radeon_r100.c:714: Can't 
enable IRQ/MSI because no handler is installed
[ 19618.266465] warning: 
/usr/src/sys/external/bsd/drm2/dist/drm/radeon/radeon_r100.c:714: Can't 
enable IRQ/MSI because no handler is installed

repeated a lot of times! what's this?

What happen is, typically under X11, I see the internal LCD of the 
laptop completely out of sync (like old CRT monitors loosing sync, 
remember?).
Initially, console and X11 look quite fine, no issues, then the problem 
will arise.
I suppose it can happen if the machine is under load, swap, high CPU, 
but no full proof.

Even if I remotely log and kill X, console comes not up again, actually 
console remains flickering (I can guess it is a console with text and 
not X11 anymore)

In dmesg I see this:
[     5.342128] kern info: [drm] Supports vblank timestamp caching Rev 2 
(21.10.2013).
[     5.342128] kern info: [drm] Driver supports precise vblank 
timestamp query.
[     5.342128] radeon0: info: radeon: MSI limited to 32-bit
[     5.342128] radeon0: interrupting at ioapic0 pin 17 (radeon0)
[     5.342128] kern info: [drm] radeon: irq initialized.
[     5.342128] kern info: [drm] Loading R300 Microcode
[     5.392154] kern info: [drm] radeon: ring at 0x0000000080001000
[     5.532225] kern error: 
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/radeon/radeon_r100.c:3701)r100_ring_test] 
*ERROR* radeon: ring test failed (scratch(0x15E4)=0xCAFEDEAD)
[     5.532225] kern error: 
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/radeon/radeon_r100.c:1232)r100_cp_init] 
*ERROR* radeon: cp isn't working (-22).
[     5.532225] radeon0: autoconfiguration error: error: failed 
initializing CP (-22).
[     5.532225] radeon0: autoconfiguration error: error: Disabling GPU 
acceleration
[     5.662291] kern error: 
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/radeon/radeon_r100.c:1252)r100_cp_fini] 
*ERROR* Wait for CP idle timeout, shutting down CP.
[     5.792358] kern warning: Failed to wait GUI idle while programming 
pipes. Bad things might happen.
[     5.792358] kern info: [drm] radeon: cp finalized


which is not very nice... "bad things might happen".... maybe this is 
one of the bad things?

Riccardo