[PATCH 3/3] drm/amd: Add safety check to make sure RLC is only turned off while in GFXOFF

[Limonciello, Mario]

On 5/16/2023 4:39 PM, Alex Deucher wrote:
> On Tue, May 16, 2023 at 2:15 PM Mario Limonciello
> <mario.limonciello at amd.com> wrote:
>> On GFX11 if RLC is stopped when not in GFXOFF the system will hang.
>> Prevent this case from ever happening.
>>
>> Tested-by: Juan Martinez <Juan.Martinez at amd.com>
>> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
>> index dcbdb2641086..f1f879d9ed8d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
>> @@ -1766,6 +1766,10 @@ static void gfx_v11_0_rlc_stop(struct amdgpu_device *adev)
>>   {
>>          u32 tmp = RREG32_SOC15(GC, 0, regRLC_CNTL);
>>
>> +       if (!adev->gfx.gfx_off_state) {
>> +               dev_err(adev->dev, "GFX is not in GFXOFF\n");
>> +               return;
>> +       }
> This should move up before the RREG above?  Also, I think it would be
> cleaner to just not mess with the RLC in S0i3.  Can we just return
> early in smu_disable_dpms() for the APU case?  All of the DPM features
> are controlled by the SMU so that function is mostly a nop of APUs
> anyway.
>
> Alex
That was what the original attempt did when we first identified this issue.
Unfortunately though just skipping RLC (without patches 1 and 2) means
that GFXOFF still either doesn't get toggled at suspend entry or isn't fully

off at suspend entry.

This leads to the graphics core behaving erratically upon resume.

So if you're OK with patches 1 and 2, I'll adjust patch 3 to also skip 
RLC for
APU.