https://bugzilla.kernel.org/show_bug.cgi?id=208839
Bug ID: 208839 Summary: AMDGPU: DPM is not enabled after hibernate and resume for CIK/Hawaii GPUs (e.g R9 390) Product: Drivers Version: 2.5 Kernel Version: 5.8 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: Video(DRI - non Intel) Assignee: drivers_video-dri@kernel-bugs.osdl.org Reporter: sandy.8925@gmail.com Regression: No
Created attachment 290801 --> https://bugzilla.kernel.org/attachment.cgi?id=290801&action=edit Resume after suspend ftrace
After hibernating and resuming, DPM is not enabled. This remains the case even if you test hibernate using the steps here: https://www.kernel.org/doc/html/latest/power/basic-pm-debugging.html
I debugged the problem, and figured out that in the file hardwaremanager.c, in the function, phm_enable_dynamic_state_management(), the check 'if (!hwmgr->pp_one_vf && smum_is_dpm_running(hwmgr) && !amdgpu_passthrough(adev) && adev->in_suspend)' returns true for the hibernate case, and false for the suspend case.
This means that for the hibernate case, the AMDGPU driver doesn't enable DPM (even though it should) and simply returns from that function. In the suspend case, it goes ahead and enables DPM, even though it doesn't need to.
I debugged further, and found out that in the case of suspend, for the CIK/Hawaii GPUs, smum_is_dpm_running(hwmgr) returns false, while in the case of hibernate, smum_is_dpm_running(hwmgr) returns true.
For CIK, the function ci_is_smc_ram_running() is ultimately used to determine if DPM is currentle enabled or not, and this seems to provide the wrong answer.
I've attached ftrace traces for the resume after suspend and resume after hibernate cases (with some functions excluded for brevity).