Re: [PATCH 2/9] thunderbolt: Add USB4 port devices

Heikki Krogerus
2021-05-19T15:30:25Z

On Wed, May 19, 2021 at 06:14:47PM +0300, Heikki Krogerus wrote:
> On Wed, May 19, 2021 at 05:12:52PM +0300, Mika Westerberg wrote:
> > Create devices for each USB4 port. This is needed when we add retimer
> > access when there is no device connected but may be useful for other
> > purposes too following what USB subsystem does. This exports a single
> > attribute "link" that shows the type of the USB4 link (or "none" if
> > there is no cable connected).
>
> <snip>
>
> > +/*
> > + * USB4 port device
> > + *
> > + * Copyright (C) 2021, Intel Corporation
> > + * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
> > + */
> > +
> > +#include <linux/acpi.h>
> > +#include <linux/pm_runtime.h>
> > +
> > +#include "tb.h"
> > +
> > +static ssize_t link_show(struct device *dev, struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct usb4_port *usb4 = tb_to_usb4_port_device(dev);
> > + struct tb_port *port = usb4->port;
> > + struct tb *tb = port->sw->tb;
> > + const char *link;
> > +
> > + if (mutex_lock_interruptible(&tb->lock))
> > + return -ERESTARTSYS;
> > +
> > + if (tb_is_upstream_port(port))
> > + link = port->sw->link_usb4 ? "usb4" : "tbt";
> > + else if (tb_port_has_remote(port))
> > + link = port->remote->sw->link_usb4 ? "usb4" : "tbt";
> > + else
> > + link = "none";
> > +
> > + mutex_unlock(&tb->lock);
> > +
> > + return sysfs_emit(buf, "%s\n", link);
> > +}
> > +static DEVICE_ATTR_RO(link);
> > +
> > +static struct attribute *common_attrs[] = {
> > + &dev_attr_link.attr,
> > + NULL
> > +};
> > +
> > +static const struct attribute_group common_group = {
> > + .attrs = common_attrs,
> > +};
> > +
> > +static const struct attribute_group *usb4_port_device_groups[] = {
> > + &common_group,
> > + NULL
> > +};
> > +
> > +static void usb4_port_device_release(struct device *dev)
> > +{
> > + struct usb4_port *usb4 = container_of(dev, struct usb4_port, dev);
> > +
> > + kfree(usb4);
> > +}
> > +
> > +struct device_type usb4_port_device_type = {
> > + .name = "usb4_port",
> > + .groups = usb4_port_device_groups,
> > + .release = usb4_port_device_release,
> > +};
>
> I noticed that in the next patch you add acpi_bus_type for these
> ports, but is that really necessary? Why not just:
>
> int usb4_port_fwnode_match(struct tb_port *port, struct fwnode_handle *fwnode)
> {
> if (is_acpi_device_node(fwnode))
> return acpi_device_adr(to_acpi_device_node(fwnode)) == port->port;
>
> return 0;
> }
>
> > +/**
> > + * usb4_port_device_add() - Add USB4 port device
> > + * @port: Lane 0 adapter port to add the USB4 port
> > + *
> > + * Creates and registers a USB4 port device for @port. Returns the new
> > + * USB4 port device pointer or ERR_PTR() in case of error.
> > + */
> > +struct usb4_port *usb4_port_device_add(struct tb_port *port)
> > +{
>
> struct fwnode_handle *child;
>
> > + struct usb4_port *usb4;
> > + int ret;
> > +
> > + usb4 = kzalloc(sizeof(*usb4), GFP_KERNEL);
> > + if (!usb4)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + usb4->port = port;
> > + usb4->dev.type = &usb4_port_device_type;
> > + usb4->dev.parent = &port->sw->dev;
> > + dev_set_name(&usb4->dev, "usb4_port%d", port->port);
>
> and then here something like this (feel free to improve this part):
>
> device_for_each_child_node(&port->sw->dev, child) {
> if (usb4_port_fwnode_match(port, child)) {
> usb4->dev.fwnode = child;
> break;
> }
> }
>
> Or maybe I'm missing something?

Ah, the node hierarchy is much more complex than I though.

Sorry for the noise.

thanks,

--
heikki