On Fri, Jul 27, 2012 at 01:46:25PM +0200, Jean Delvare wrote: > Right now we have support for explicit platform device IDs, as well as > ID-less platform devices when a given device type can only have one > instance. However there are cases where multiple instances of a device > type can exist, and their IDs aren't (and can't be) known in advance > and do not matter. In that case we need automatic device IDs to avoid > device name collisions. > > I am using magic ID value -4 for this (I left -2 and -3 free in case > we ever need a couple of other magic values.) The automatically > allocated device IDs are global (to avoid an additional per-driver > cost) and are stored internally as negative numbers, starting with -4. > This is required so that the IDs can be freed later. Externally the > positive value is used. > > Signed-off-by: Jean Delvare <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > --- > If anyone has a problem with the -4 or using negative device IDs > internally, it would be possible to avoid that by adding a boolean > attribute to every platform device to record whether the ID needs to > be freed. This would cost some memory.
A boolean is "free" don't worry about that. Don't overload the device id with "magic" values like this, I don't like that at all. I'd prefer to see another field added if this is really going to be needed. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
