On Sun, 3 May 2009, Pantelis Koukousoulas wrote: > Hi, > > > It has not been worked on. There was a lot of discussion, and we sort > > of reached a consensus about what was needed, but no patches have been > > posted. > > Could you please point me towards / inform me about what was that consensus? > I got lost in the various threads after a while :) As I recall, it went something like this: There should be a mechanism for userspace to influence automatic binding of the generic driver to USB devices. If a program wants to gain control a newly-detected device then it can; otherwise the generic driver will handle it in the usual way. Also, there should be some way for a user program to take control of an existing device. When a user program gains control of a device, the kernel won't automatically install any configuration and won't probe for drivers when the config is changed. Instead the user program is granted full control over all the interfaces. It can do Set-Config or Reset whenever it wants. Other programs will be allowed to do harmless input via usbfs (like reading the descriptors from the device file) but not any ioctls. And nobody will be allowed to write to the bConfigurationValue sysfs attribute. When the user program gives up control of a device, the kernel won't automatically issue any Set-Interface requests (I'm not sure this is really a good idea). It also won't change the configuration or automatically probe for interface drivers. This doesn't answer all the remaining questions, but it is a start. > >> P.S., note that it would be fine for my usecase if the user has to > >> unplug the device, turn it off even > >> and replug it after the port is "grabbed" to make sure the device is > >> in a clean state. > Surely the goal is to "grab" devices. But since these grabs must persist across > resets/disconnects/reconnects we would effectively grab "ports", right? No, I don't think so. It doesn't make sense to grab a port. Instead we would allow the program to intercept all new device registrations somehow and decide whether or not to take control of the device. 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
