HACK: iommu: apple-dart: workaround broken runtime PM with PCIe devices

Runtime PM behaves strangely with PCIe devices, pm_runtime_enabled()
returns true here although the devices do not support runtime PM.
This seems to confuse the PM core and DART is runtime suspended while
the device is in use. The dart_hw_reset() in the resume path ends up
breaking PCIe devices eventually.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/iommu/apple-dart.c

@@ -764,15 +764,24 @@ static struct iommu_device *apple_dart_probe_device(struct device *dev)
 {
 	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
 	struct apple_dart_stream_map *stream_map;
+	u32 dl_flags = DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER;
 	int i;
 
 	if (!cfg)
 		return ERR_PTR(-ENODEV);
 
+	/*
+	 * Runtime PM behaves strangely with PCIe devices, pm_runtime_enabled()
+	 * returns true here although the devices do not support runtime PM.
+	 * This seems to confuse the PM core and DART is runtime suspended while
+	 * the device is in use. The dart_hw_reset() in the resume path ends up
+	 * breaking PCIe devices eventually.
+	 */
+	if (dev_is_pci(dev))
+		dl_flags |= DL_FLAG_RPM_ACTIVE;
+
 	for_each_stream_map(i, cfg, stream_map)
-		device_link_add(
-			dev, stream_map->dart->dev,
-			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
+		device_link_add(dev, stream_map->dart->dev, dl_flags);
 
 	return &cfg->stream_maps[0].dart->iommu;
 }