[PATCH] drm/amdgpu: add safeguards for accessing mmhub CG registers

[Yu, Lang]

[Public]

Hi Lijo,

For cyan skillfish, both adev->cg_flags and adev->pg_flags are zero. I just found "RREG32_SOC15(MMHUB, 0, mmMM_ATC_L2_MISC_CG);" in mmhub_v2_0_get_clockgating() caused a gpu hang(cat amdgpu_pm_info). I didn't check if it's some sort of PG which causes the issue.

Regards,
Lang

From: Lazar, Lijo <Lijo.Lazar at amd.com>
Sent: Wednesday, January 26, 2022 8:06 PM
To: Yu, Lang <Lang.Yu at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Deucher, Alexander <Alexander.Deucher at amd.com>; Huang, Ray <Ray.Huang at amd.com>; Yu, Lang <Lang.Yu at amd.com>
Subject: Re: [PATCH] drm/amdgpu: add safeguards for accessing mmhub CG registers


[Public]

Hi Lang,

There are ASICs in which driver doesn't enable CG, and then these flags will be false. However, the CG will be enabled by another component like VBIOS. Driver still reports the CG status eventhough driver doesn't enable it. For those, this logic doesn't work.

BTW, could you check if it's some sort of PG which causes the issue?

Thanks,
Lijo
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