On Mon, Jun 6, 2011 at 1:56 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > Hi, > > While working on my cleanup / v4l2 compliance series for > the pwc driver I've noticed that the pwc and gspca drivers > are doing different things wrt what error they return to > an app is using the device while it gets unplugged. > gspca returns -ENODEV, where as pwc returns -EPIPE. > > Both make some sense. I've not looked at what other > usb (or other hotplug capable bus) v4l2 drivers do, but > it makes sense to me to standardize on an error here, > preferably a reasonable unique one so that apps can > detect unplug versus other errors. Note that the usb > subsystem returns -ENODEV when you try to (re)submit > an urb from its completion handler, when that > completion handler gets called because the urb was > unlinked because of device unplug. > > Given that we often return usb error codes unmodified > and the usb subsys uses -ENODEV for trying to do things > with unplugged devices, I guess it makes sense for > us to also use -ENODEV. I'm pretty sure ENODEV is what gets returned today if you attempt to open a /dev/videoX node for a device that has been disconnected but the device node hasn't yet been removed. So I would agree that ENODEV is a good choice for the scenario you described. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
