"For those devices, the first call to pcmcia_register_driver will fail"
No, the first call is still going to succeed. Remember, you can load a module (and therefore register the driver) for a device which is not yet present!
"For those devices, the first call to pcmcia_ register_ driver will fail"
No, the first call is still going to succeed. Remember, you can load a module (and therefore register the driver) for a device which is not yet present!