Re: [RFC PATCH 06/10] usb: xhci: Add Tegra XHCI host-controller driver

On Thu, May 15, 2014 at 10:17:10AM +0200, Arnd Bergmann wrote:

On Wednesday 14 May 2014 17:33:02 Andrew Bresticker wrote:

[...]

quoted

+	/* Create child xhci-plat device */
+	memset(xhci_resources, 0, sizeof(xhci_resources));
+	res = platform_get_resource(to_platform_device(dev), IORESOURCE_IRQ, 0);
+	if (!res) {
+		dev_err(dev, "Missing XHCI IRQ\n");
+		ret = -ENODEV;
+		goto out;
+	}
+	xhci_resources[0].start = res->start;
+	xhci_resources[0].end = res->end;
+	xhci_resources[0].flags = res->flags;
+	xhci_resources[0].name = res->name;
+	res = platform_get_resource(to_platform_device(dev), IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "Missing XHCI registers\n");
+		ret = -ENODEV;
+		goto out;
+	}
+	xhci_resources[1].start = res->start;
+	xhci_resources[1].end = res->end;
+	xhci_resources[1].flags = res->flags;
+	xhci_resources[1].name = res->name;
+
+	xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);
+	if (!xhci) {
+		dev_err(dev, "Failed to allocate XHCI host\n");
+		ret = -ENOMEM;
+		goto out;
+	}

This does not feel appropriate at all: Rather than creating a child device,
you should have a specific driver that hooks into functions exported
by the xhci core. See Documentation/driver-model/design-patterns.txt

I don't think Documentation/driver-model/design-patterns.txt documents
this. Perhaps this is what you had in mind?

	http://lwn.net/Articles/336262/

Thierry