staging: vchiq: Use the old dma controller for OF config on platform …

…devices

vchiq on Pi4 is no longer under the soc node, therefore it
doesn't get the dma-ranges for the VPU.

Switch to using the configuration of the old dma controller as
that will set the dma-ranges correctly.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -3599,6 +3599,7 @@ vchiq_register_child(struct platform_device *pdev, const char *name)
 {
 	struct platform_device_info pdevinfo;
 	struct platform_device *new_dev;
+	struct device_node *np;
 
 	memset(&pdevinfo, 0, sizeof(pdevinfo));
 
@@ -3612,10 +3613,20 @@ vchiq_register_child(struct platform_device *pdev, const char *name)
 		return NULL;
 
 	/*
-	 * We want the dma-ranges etc to be copied from the parent VCHIQ device
-	 * to be passed on to the children too.
+	 * We want the dma-ranges etc to be copied from a device with the
+	 * correct dma-ranges for the VPU.
+	 * VCHIQ on Pi4 is now under scb which doesn't get those dma-ranges.
+	 * Take the "dma" node as going to be suitable as it sees the world
+	 * through the same eyes as the VPU.
 	 */
-	of_dma_configure(&new_dev->dev, pdev->dev.of_node, true);
+	np = of_find_node_by_path("dma");
+	if (!np)
+		np = pdev->dev.of_node;
+
+	of_dma_configure(&new_dev->dev, np, true);
+
+	if (np != pdev->dev.of_node)
+		of_node_put(np);
 
 	return new_dev;
 }