kern/51029: radeon DRMKMS deadlocks on my hw

[macallan%netbsd.org@localhost]

>Number:         51029
>Category:       kern
>Synopsis:       radeon DRMKMS deadlocks on my hw
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 30 16:55:00 +0000 2016
>Originator:     Michael
>Release:        7.99.26
>Organization:
>Environment:
NetBSD paddy 7.99.26 NetBSD 7.99.26 (CONNEMARA) #3: Thu Feb  4 00:32:33 EST 2016  root@paddy:/home/build/obj_amd64/sys/arch/amd64/compile/CONNEMARA amd64

>Description:
radeondrmkms will deadlock the machine when trying to switch video modes on initialization, with the hardware in some more or less undefined state with an unreadable display.

Relevant dmesg parts with old DRM:
cpu0 at mainbus0 apid 0
cpu0: AMD Turion(tm) 64 X2 Mobile Technology TL-60, id 0x60f82
cpu1 at mainbus0 apid 1
cpu1: AMD Turion(tm) 64 X2 Mobile Technology TL-60, id 0x60f82
...
acpi0 at mainbus0: Intel ACPICA 20160108
acpi0: X/RSDT: OemId <GATEWA,SYSTEM  ,20080523>, AslId < LTP,00000000>
acpi0: MCFG: segment 0, bus 0-11, address 0x00000000e0000000
acpi0: SCI interrupting at int 9
...
acpivga0 at acpi0 (VGA): ACPI Display Adapter
acpiout0 at acpivga0 (CRT, 0x0100): ACPI Display Output Device
acpiout1 at acpivga0 (TV0, 0x0210): ACPI Display Output Device
acpiout2 at acpivga0 (LCD, 0x0110): ACPI Display Output Device
acpiout2: brightness levels: [12,25,37,50,62,75,87,100]
acpivga0: connected output devices:
acpivga0:   0x0100 (acpiout0): Ext. Monitor, head 0, bios detect
acpivga0:   0x0110 (acpiout2): LCD Panel, head 0, bios detect
acpivga0:   0x0210 (acpiout1): Unknown Output Device, head 0, bios detect
...
genfb0 at pci1 dev 5 function 0: vendor 1002 product 791f (rev. 0x00)
genfb0: framebuffer at 0xf0000000, size 1024x768, depth 32, stride 4096
wsdisplay0 at genfb0 kbdmux 1: console (default, vt100 emulation), using wskbd0
wsmux1: connecting to wsdisplay0
radeondrm0 at genfb0: ATI Radeon RS690 X1270 IGP
radeondrm0: Initialized radeon 1.29.0 20080613

With old DRM at least Xorg is able to switch to the display's native resolution, but even there acceleration doesn't work ( used to though ) - the driver complains about the drawing engine never to go idle.

Some Xorg.0.log bits:
[  2826.360] (--) PCI:*(1:1:5:0) 1002:791f:107b:0381 rev 0, Mem @ 0xf0000000/134217728, 0xf8100000/65536, 0xf8000000/1048576, I/O @ 0x00009000/256
...
[  2826.962] (II) RADEON(0): ATOM BIOS Rom: 
[  2826.962]    SubsystemVendorID: 0x107b SubsystemID: 0x0381
[  2826.962]    IOBaseAddress: 0x9000
[  2826.962]    Filename: BR27705.bin 
[  2826.962]    BIOS Bootup Message: 
ATI Radeon Xpress for SA1A                                                  

[  2826.962] (II) RADEON(0): Framebuffer space used by Firmware (kb): 16
[  2826.962] (II) RADEON(0): Start of VRAM area used by Firmware: 0x7ffc000
[  2826.962] (II) RADEON(0): AtomBIOS requests 16kB of VRAM scratch space
[  2826.962] (II) RADEON(0): AtomBIOS VRAM scratch base: 0x7ffc000
[  2826.962] (II) RADEON(0): Cannot get VRAM scratch space. Allocating in main memory instead
[  2826.962] (II) RADEON(0): Default Engine Clock: 400000
[  2826.962] (II) RADEON(0): Default Memory Clock: 200000
[  2826.962] (II) RADEON(0): Maximum Pixel ClockPLL Frequency Output: 1200000
[  2826.963] (II) RADEON(0): Minimum Pixel ClockPLL Frequency Output: 0
[  2826.963] (II) RADEON(0): Maximum Pixel ClockPLL Frequency Input: 13500
[  2826.963] (II) RADEON(0): Minimum Pixel ClockPLL Frequency Input: 1000[  2826.963] (II) RADEON(0): Maximum Pixel Clock: 400000
[  2826.963] (II) RADEON(0): Reference Clock: 14320
[  2826.963] (WW) RADEON(0): [dri] Acceleration disabled, not initializing the DRI
[  2826.963] (II) RADEON(0): Generation 2 PCI interface, using max accessible memory
[  2826.963] (II) RADEON(0): Detected total video RAM=131072K, accessible=131072K (PCI BAR=131072K)
[  2826.963] (--) RADEON(0): Mapped VideoRAM: 131072 kByte (128 bit DDR SDRAM)
[  2826.963] (II) RADEON(0): Color tiling enabled by default


>How-To-Repeat:
try to run a kernel with new radeomdrmkms on this hw
>Fix:
n/a