That should be "MODULE_PARM_DESC(pb_fn_mode, ...)". Also, since this is
for compatibility with ADB, why do we have 3 options? Doesn't ADB have
only 2?

No, the ADB keyboard can operate in 2 modes that can be set with a PMU
command, I forgot about that in my earlier comments. In one mode, you get
the "special" behaviour by default on the Fx keys and you get Fx when
pressing Fn-Fx, and in the other mode, you get the Fx by default and the
special behaviour when pressing Fn-Fx.

quoted

+static inline struct hidinput_key_translation *find_translation(

I thought is was agreed that we'd avoid "inlines" in .c files?

Ah ? I have certainly missed that discussion ...

quoted

+	struct hidinput_key_translation *table, u16 from)
+{
+	struct hidinput_key_translation *trans;
+
+	/* Look for the translation */
+	for(trans = table; trans->from && (trans->from != from); trans++);
+
+	return (trans->from?trans:NULL);
+}

I'd prefer liberal amount of spaces applied here </extreme nitpick mode>

Me too :)

quoted

+		try_translate = test_bit(usage->code, usbhid_pb_numlock)?1:
+				test_bit(LED_NUML, input->led);
+		if (try_translate) {

Isn't this the same as 

		if (test_bit(usage->code, usbhid_pb_numlock) || test_bit(LED_NUML, input->led))

but harder to read?

No. If the first one is 0, the second one will not matter in the first
version, while it will in yours.

Ben.