drm/nouveau: Runtime suspend despite HDA being unbound

Commit 5addcf0a5f0f ("nouveau: add runtime PM support (v0.9)") prevents
runtime suspend of the GPU if its integrated HDA controller is not bound
to a driver.  The rationale appears to be that probing the HDA fails if
the GPU is in D3cold.

However we now use a device link to ensure that the GPU is runtime
resumed while the HDA controller is probed, rendering this safety
measure obsolete.  Remove it.

Cc: Dave Airlie <airlied@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
Tested-by: Denis Lisov <dennis.lissov@gmail.com>       # Nvidia Optimus
Tested-by: Peter Wu <peter@lekensteyn.nl>              # Nvidia Optimus
Tested-by: Lukas Wunner <lukas@wunner.de>              # MacBook Pro
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://patchwork.freedesktop.org/patch/msgid/77e0ab74f3377ea9b6acf8fab624acfb4f7dbeca.1520068884.git.lukas@wunner.de

drivers/gpu/drm/nouveau/nouveau_drm.c

@@ -510,37 +510,6 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
 	return 0;
 }
 
-#define PCI_CLASS_MULTIMEDIA_HD_AUDIO 0x0403
-
-static void
-nouveau_get_hdmi_dev(struct nouveau_drm *drm)
-{
-	struct pci_dev *pdev = drm->dev->pdev;
-
-	if (!pdev) {
-		NV_DEBUG(drm, "not a PCI device; no HDMI\n");
-		drm->hdmi_device = NULL;
-		return;
-	}
-
-	/* subfunction one is a hdmi audio device? */
-	drm->hdmi_device = pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
-						(unsigned int)pdev->bus->number,
-						PCI_DEVFN(PCI_SLOT(pdev->devfn), 1));
-
-	if (!drm->hdmi_device) {
-		NV_DEBUG(drm, "hdmi device not found %d %d %d\n", pdev->bus->number, PCI_SLOT(pdev->devfn), 1);
-		return;
-	}
-
-	if ((drm->hdmi_device->class >> 8) != PCI_CLASS_MULTIMEDIA_HD_AUDIO) {
-		NV_DEBUG(drm, "possible hdmi device not audio %d\n", drm->hdmi_device->class);
-		pci_dev_put(drm->hdmi_device);
-		drm->hdmi_device = NULL;
-		return;
-	}
-}
-
 static int
 nouveau_drm_load(struct drm_device *dev, unsigned long flags)
 {
@@ -568,8 +537,6 @@ nouveau_drm_load(struct drm_device *dev, unsigned long flags)
 	INIT_LIST_HEAD(&drm->clients);
 	spin_lock_init(&drm->tile.lock);
 
-	nouveau_get_hdmi_dev(drm);
-
 	/* workaround an odd issue on nvc1 by disabling the device's
 	 * nosnoop capability.  hopefully won't cause issues until a
 	 * better fix is found - assuming there is one...
@@ -655,8 +622,6 @@ nouveau_drm_unload(struct drm_device *dev)
 	nouveau_ttm_fini(drm);
 	nouveau_vga_fini(drm);
 
-	if (drm->hdmi_device)
-		pci_dev_put(drm->hdmi_device);
 	nouveau_cli_fini(&drm->client);
 	nouveau_cli_fini(&drm->master);
 	kfree(drm);
@@ -911,15 +876,6 @@ nouveau_pmops_runtime_idle(struct device *dev)
 		return -EBUSY;
 	}
 
-	/* if we have a hdmi audio device - make sure it has a driver loaded */
-	if (drm->hdmi_device) {
-		if (!drm->hdmi_device->driver) {
-			DRM_DEBUG_DRIVER("failing to power off - no HDMI audio driver loaded\n");
-			pm_runtime_mark_last_busy(dev);
-			return -EBUSY;
-		}
-	}
-
 	list_for_each_entry(crtc, &drm->dev->mode_config.crtc_list, head) {
 		if (crtc->enabled) {
 			DRM_DEBUG_DRIVER("failing to power off - crtc active\n");

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -208,7 +208,6 @@ struct nouveau_drm {
 	bool have_disp_power_ref;
 
 	struct dev_pm_domain vga_pm_domain;
-	struct pci_dev *hdmi_device;
 };
 
 static inline struct nouveau_drm *