Re: [PATCH] drm/amdgpu: keep mmhub clock gating being enabled during s2idle suspend

["Lazar, Lijo" <lijo.lazar@amd.com>]

On 4/25/2022 12:22 PM, Prike Liang wrote:
> Without MMHUB clock gating being enabled then MMHUB will not disconnect
> from DF and will result in DF C-state entry can't be accessed during S2idle
> suspend, and eventually s0ix entry will be blocked.
> 
> Signed-off-by: Prike Liang <Prike.Liang@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> index a455e59f41f4..20946bc7fc93 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> @@ -1151,6 +1151,16 @@ static int gmc_v10_0_set_clockgating_state(void *handle,
>   	int r;
>   	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>   
> +	/*
> +	 * The issue mmhub can't disconnect from DF with MMHUB clock gating being disabled
> +	 * is a new problem observed at DF 3.0.3, however with the same suspend sequence not
> +	 * seen any issue on the DF 3.0.2 series platform.
> +	 */
> +	if (adev->in_s0ix && adev->ip_versions[DF_HWIP][0] > IP_VERSION(3, 0, 2)) {
> +		dev_dbg(adev->dev, "keep mmhub clock gating being enabled for s0ix\n");
> +		return 0;
> +	}
> +

This only ignores clock gating requests as long as s0ix flag is set. As 
far as I see, s0ix flag is set to true even during resume and set to 
false only after resume is completed. Is that intention and is this 
tested to be working fine? I suggest to keep this specifically for 
suspend calls.

Thanks,
Lijo

>   	r = adev->mmhub.funcs->set_clockgating(adev, state);
>   	if (r)
>   		return r;
>