[Bug 199959] amdgpu, regression?: system freezes after resume

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=199959

--- Comment #13 from Christian König (christian.koenig at amd.com) ---
(In reply to Alexander Mezin from comment #11)
> I literally have no idea what I'm doing, but adding
> 'amdgpu_device_resize_fb_bar(adev);' line to all 'gmc_v?_?_resume()'
> (because I don't know which version is used for my card) "fixed" it somehow.
> Resume works, but there are some artifacts on screen during resume (they
> flash only once and then disappear). Before 'amdgpu_device_resize_fb_bar'
> was introduced, there were no artifacts at all.

Hehe, yeah that was a really nice test and confirms my suspicion on what's
going wrong here.

Because you tried to resize the BAR once more after resume the resources in the
address space are freed up and allocated again:
[  212.484672] amdgpu 0000:65:00.0: BAR 2: releasing [mem
0xe200000000-0xe2001fffff 64bit pref]
[  212.484673] amdgpu 0000:65:00.0: BAR 0: releasing [mem
0xe000000000-0xe1ffffffff 64bit pref]
[  212.484683] pcieport 0000:64:00.0: BAR 15: releasing [mem
0xe000000000-0xe2ffffffff 64bit pref]

[  212.484691] pcieport 0000:64:00.0: BAR 15: assigned [mem
0xe000000000-0xe2ffffffff 64bit pref]
[  212.484692] amdgpu 0000:65:00.0: BAR 0: assigned [mem
0xe000000000-0xe1ffffffff 64bit pref]
[  212.484697] amdgpu 0000:65:00.0: BAR 2: assigned [mem
0xe200000000-0xe2001fffff 64bit pref]

Since it allocates the exact same address we freed up before the real issue is
not the address itself, but that fact that the hardware config isn't saved
during suspend/resume.

That strongly looks like a bug in the BIOS and/or the Linux PCI subsystem
driver for Intel hardware to me.

I will try to narrow this down with a few patches on Monday, but don't expect
any quick fix.

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