[PATCH V2 3/5] drm/amdgpu: correct the audio function initial Dstate

[Lazar, Lijo]

On 6/4/2021 3:28 PM, Evan Quan wrote:
> On driver loading, the ASIC is in D0 state. The bundled
> audio function should be in the same state also.
> 
> Change-Id: I136e196be7633e95883a7f6c33963f7583e9bad1
> Signed-off-by: Evan Quan <evan.quan at amd.com>
> ---
> V1->V2:
>    - Lijo: include the code in a seperate API for better readability
>    - limit the change for Navi10 and later dGPUs
>    - comments more about the background
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 40 +++++++++++++++++++++++++
>   1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> index c354ffa62483..e9f2161738d1 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> @@ -123,6 +123,22 @@ void amdgpu_register_gpu_instance(struct amdgpu_device *adev)
>   	mutex_unlock(&mgpu_info.mutex);
>   }
>   
> +static void amdgpu_get_audio_func(struct amdgpu_device *adev)
> +{
> +	struct pci_dev *p = NULL;
> +
> +	p = pci_get_domain_bus_and_slot(pci_domain_nr(adev->pdev->bus),
> +			adev->pdev->bus->number, 1);
> +	if (p) {
> +		pm_runtime_get_sync(&p->dev);
> +
> +		pm_runtime_mark_last_busy(&p->dev);
> +		pm_runtime_put_autosuspend(&p->dev);
> +
> +		pci_dev_put(p);
> +	}
> +}
> +
>   /**
>    * amdgpu_driver_load_kms - Main load function for KMS.
>    *
> @@ -212,9 +228,33 @@ int amdgpu_driver_load_kms(struct amdgpu_device *adev, unsigned long flags)
>   						DPM_FLAG_MAY_SKIP_RESUME);
>   		pm_runtime_use_autosuspend(dev->dev);
>   		pm_runtime_set_autosuspend_delay(dev->dev, 5000);
> +
>   		pm_runtime_allow(dev->dev);
> +
>   		pm_runtime_mark_last_busy(dev->dev);
>   		pm_runtime_put_autosuspend(dev->dev);
> +
> +		/*
> +		 * For runpm implemented via BACO, PMFW will handle the
> +		 * timing for BACO in and out:
> +		 *   - put ASIC into BACO state only when both video and
> +		 *     audio functions are in D3 state.
> +		 *   - pull ASIC out of BACO state when either video or
> +		 *     audio function is in D0 state.
> +		 * Also, at startup, PMFW assumes both functions are in
> +		 * D0 state.
> +		 *
> +		 * So if snd driver was loaded prior to amdgpu driver
> +		 * and audio function was put into D3 state behind PMFW's
> +		 * back, the BACO may not correctly kicks in and out.
> +		 *
> +		 * Via amdgpu_get_audio_func() below, the audio function
> +		 * is guarded to be in D0 correctly.
> +		 */

On a second look at the comments - should runpm _get on audio dev be 
done before doing device_init (so that it's in D0 while FW is getting 
loaded) and put done here?

Thanks,
Lijo

> +		if (amdgpu_device_supports_baco(dev) &&
> +		    !(adev->flags & AMD_IS_APU) &&
> +		    (adev->asic_type >= CHIP_NAVI10))
> +			amdgpu_get_audio_func(adev);
>   	}
>   
>   	if (amdgpu_acpi_smart_shift_update(dev, AMDGPU_SS_DRV_LOAD))
>