[PATCH V3 3/5] drm/amdgpu: make audio dev's D-state transition PMFW-aware

[Evan Quan]

To correctly kick into BACO state, the audio dev's D-state
transition(D0->D3) needs to be PMFW-aware. So, if the audio
dev entered D3 state prior to our driver, we need to bring
it back to D0 state and make sure there will be a D-state
transition on runpm suspend.

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
v2->V3:
  - Lijo: update the code comment further
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 42 +++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index c354ffa62483..131ae2a17abf 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 +228,35 @@ 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, there will
+		 * be no PMFW-aware D-state transition(D0->D3) on runpm
+		 * suspend. Thus the BACO will be not correctly kicked in.
+		 *
+		 * Via amdgpu_get_audio_func(), the audio dev is put
+		 * into D0 state. Then there will be a PMFW-aware D-state
+		 * transition(D0->D3) on runpm suspend.
+		 */
+		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))
-- 
2.29.0