On Thu, 11 Apr 2013, Andrzej Pietrasiewicz wrote: > This adds a new sysfs root device to serve as a replacement for > devices which are available only when a gadget is being bound. > > It is motivated by adding configfs support to USB Ethernet functions. > When configfs is there, we would like to be able to mkdir some function > directory, e.g.: > > $ mkdir functions/ecm.usb0 > > and have the usb0 available in the system (albeit in an unconfigured, > or default state) at this very point, which is _way_ before the gadget What do you mean by "available in the system"? > is actually bound. However, this poses a chicken and egg problem. > In order for the interface to appear in the system, it needs to be What interface are you talking about? Is it a USB interface, a network interface, a programming interface, a user interface, or some other sort of interface? > registered with register_netdev. But in order to register it, its > parent device must be known and it becomes known only later during > gadget's bind. Why must this happen before the gadget driver is bound? What can't it happen after the driver is bound and before the gadget is connected to a host? > This patch adds a /sys/devices/usb_gadget root device, which is registered > during module_init of libcomposite, so it is available at any time for > all libcomposite users and is used as a parent device for USB Ethernet > devices instead of the gadget->dev. I can't understand the reasoning here. It's like saying I should be able to configure the network settings for my ethernet controller before the e100 driver is bound to it. Are you sure this is necessary? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
