[Powerpc] Sam460ex Canyonlands issue -Kernel 4.4.6-rc1

[Michel Dänzer]

On 29.03.2016 18:55, Julian Margetson wrote:
> On 3/28/2016 11:15 PM, Michel Dänzer wrote:
>> On 29.03.2016 08:47, Julian Margetson wrote:
>>> Seeing the following when booting kernel 4.6-rc1 on Acube Sam460ex
>>> Canyonlands board.
>>> This loops for a few times then the kernel boots.
>>> No problem with the 4.6-rc1 with an A-eon Tabor Freescale e500v2 board.
>>>
>>> Regards
>>>
>>> Julian
>>>
>>>
>>>   [    2.197839] ------------[ cut here ]------------
>>>   [    2.197850] WARNING: CPU: 0 PID: 1 at
>>> drivers/gpu/drm/drm_irq.c:1368 drm_vblank_off+0x2c/0x1e0
>> That's
>>
>>     if (WARN_ON(pipe >= dev->num_crtcs))
>>
>> My best guess is that drm_vblank_off is called before drm_vblank_init,
>> so dev->num_crtcs is still 0.
>>
>>
>> Please provide the full dmesg output corresponding to the problem.
>>
>>
> Attached

[...]

> [drm] radeon: irq initialized.
> [drm:r600_ring_test] *ERROR* radeon: ring 0 test failed (scratch(0x850C)=0xCAFEDEAD)
> radeon 0001:81:00.0: disabling GPU acceleration

Okay, so the problem is that acceleration fails to initialize, in which
case the driver calls drm_vblank_cleanup.

I can see two basic options for a solution: Either don't call
radeon_irq_kms_fini/drm_vblank_cleanup if acceleration fails to
initialize, or check if acceleration is enabled before calling
drm_vblank_on/off. Any preferences?


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer