FreeBSD / amdgpu / Vega 3, pstate TEST_DEBUG_DATA: 0x0

[Andriy Gapon]

On 24/04/2020 20:22, Harry Wentland wrote:
> On 2020-04-24 8:34 a.m., Andriy Gapon wrote:
>>
>> First, I understand that my platform is not directly supported and probably not
>> very interesting, but I still hope to get some tips or pointers.
>>
> 
> Hi Andriy,
> 
> yeah, limited insight here since FreeBSD isn't something I'm familiar
> with. :)

Harry,

thanks a lot for your help.  It set me on a right path, although a bit
indirectly :-)

Let me start by saying that I was able to fix the driver.

After looking at the laptop in a dark room I could see that the backlight was
actually on, but there was no video output.

So, I went back to comparing FreeBSD and Linux logs, especially around the place
where "TEST_DEBUG_DATA: 0x0" was reported.  And then suddenly I spotted what I
missed before.  Linux reported 3 pipes while FreeBSD reported 4.  And the errors
were about the forth, non-existent, pipe -- I guess, not surprising at all.
With some additional printfs I could confirm it for sure.  So, then I looked for
the code where the number of pipes is set and almost immediately could see the
problem.

FreeBSD amdgpu has DCN_VERSION_1_01 support ifdef-ed out, for whatever reason.
Your commit "drm/amd/display: Drop DCN1_01 guards" has not been ported yet and
CONFIG_DRM_AMD_DC_DCN1_01 is not defined.  Of course, the number of pipes was
not the only thing that did not match the actual hardware/firmware because of
that.  Once I set CONFIG_DRM_AMD_DC_DCN1_01 everything just worked.

Thank you again!

>> I am trying to get amdgpu/FreeBSD going on Motile M141 laptop with Ryzen 3 3200U
>> CPU that has Vega 3 graphics integrated.  When amdgpu starts loading the screen
>> goes black and never lights up again.  I am not sure whether there is no signal
>> at all or whether the backlight is turned off, but the screen is completely
>> dark.  I can blindly interact with the system, so it's not crashed or hung.
>> From system logs I can see that the driver attaches successfully.  It recognizes
>> the hardware, loads its firmware, detects the eDP screen and so on.
>>
> 
> Does BSD have a way to check or set your backlight value manually (a la
> /sys/class/backlight on linux)? If so I'd suggest checking and setting
> it to non-zero values, ideally to max_brightness.
> 
> Have you tried an external display?
> 
>> The FreeBSD's amdgpu port that I am trying is based on code circa 5.0.
>> There is no newer version ported.
>> I tried a couple of Linux distros with 5.3.x kernels and they worked without any
>> problems. So that gives me some hope.
>>
>> I compared driver messages (with drm_debug set to 0xfff) between Linux and
>> FreeBSD and they look quite similar.  Except for one thing.
>> In the FreeBSD case there are these error messages that are not seen with Linux:
>>
>> [drm] pstate TEST_DEBUG_DATA: 0x0
>> WARNING !(0) failed at
>> /usr/home/avg/devel/kms-drm/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c:868
>> #0 0xffffffff83451633 at linux_dump_stack+0x23
>> #1 0xffffffff8325a9ee at dcn10_verify_allow_pstate_change_high+0x4e
>> #2 0xffffffff8325e925 at dcn10_wait_for_mpcc_disconnect+0x25
>> #3 0xffffffff8325de53 at dcn10_disable_plane+0x53
>> #4 0xffffffff8325c9f5 at dcn10_init_hw+0x755
>> #5 0xffffffff83295ca8 at dc_create+0x538
>> #6 0xffffffff8327a8da at dm_hw_init+0x1ea
>> #7 0xffffffff831701d1 at amdgpu_device_init+0x1b11
>> #8 0xffffffff83185177 at amdgpu_driver_load_kms+0xd7
>> #9 0xffffffff833f138e at drm_dev_register+0x17e
>> #10 0xffffffff83178dea at amdgpu_pci_probe+0x18a
>> #11 0xffffffff83456f40 at linux_pci_attach+0x560
>> #12 0xffffffff80bf68ea at device_attach+0x3ca
>> #13 0xffffffff80bf6490 at device_probe_and_attach+0x70
>> #14 0xffffffff80bf8358 at bus_generic_driver_added+0x58
>> #15 0xffffffff80bf4289 at devclass_driver_added+0x39
>> #16 0xffffffff80bf41c7 at devclass_add_driver+0x147
>> #17 0xffffffff83455ae9 at _linux_pci_register_driver+0xc9
>>
>> That warning plus stack trace is actually BREAK_TO_DEBUGGER() in the original
>> Linux code.
>> So, that makes me think that the problem is pretty serious.
> 
> BREAK_TO_DEBUGGER is probably overly scary here. It's somewhat a concern
> as this means power consumption might be higher than expected. We've
> seen this issue on several systems without any other adverse effects to
> usability.
> 
> Harry
> 
>> I tried searching for "TEST_DEBUG_DATA: 0x0" and I could not find a single
>> result with "0x0" in it.  Usually there is some non-zero value.
>> To me this looks like maybe some hardware component is not turned on...
>> Perhaps this is something relatively obvious for people that hack on the driver
>> and the hardware.
>> I hope to receive some hint about what to look for.
>> I can cherry-pick commits from Linux, apply patches, add additional debugging
>> logs, etc.
>>
>> FreeBSD amdgpu dmesg: https://people.freebsd.org/~avg/amdgpu.dmesg.txt
>> Full Linux dmesg: https://people.freebsd.org/~avg/linux-5.3.0-28.dmesg.out
>>
>> And with with drm_debug=0xfff.
>> FreeBSD: https://people.freebsd.org/~avg/fbsd-dmesg.txt
>> Linux: https://people.freebsd.org/~avg/linux-5.3.9-dmesg.txt
>>
>> I see that both Linux and FreeBSD have similar messages about failing to load
>> some microcode components, but I guess that it must be okay since Linux works:
>> [    4.487381] [drm] reserve 0x400000 from 0xf400c00000 for PSP TMR
>> [    4.564893] [drm] failed to load ucode id (12)
>> [    4.564894] [drm] psp command failed and response status is (-53233)
>> [    4.567891] [drm] failed to load ucode id (13)
>> [    4.567892] [drm] psp command failed and response status is (-65521)
>> [    4.570891] [drm] failed to load ucode id (14)
>> [    4.570892] [drm] psp command failed and response status is (-65521)



-- 
Andriy Gapon