xo1-rfkill: only act when blocked state is changed

The XO-1 rfkill driver should only send EC commands when changing
between blocked/unblocked state.

The rfkill switch is asked to be unblocked on every resume (even when
the card was never blocked before) and sending a EC_WLAN_LEAVE_RESET
command here upsets the resume sequence of the libertas driver. Adding
the check to avoid the spurious EC_WLAN_LEAVE_RESET fixes the wifi resume
behaviour.

The rfkill state is maintained by the hardware over suspend/resume
so no extra consideration is needed here.
Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/xo1-rfkill.c

@@ -15,15 +15,26 @@
 
 #include <asm/olpc.h>
 
+static bool card_blocked;
+
 static int rfkill_set_block(void *data, bool blocked)
 {
 	unsigned char cmd;
+	int r;
+
+	if (blocked == card_blocked)
+		return 0;
+
 	if (blocked)
 		cmd = EC_WLAN_ENTER_RESET;
 	else
 		cmd = EC_WLAN_LEAVE_RESET;
 
-	return olpc_ec_cmd(cmd, NULL, 0, NULL, 0);
+	r = olpc_ec_cmd(cmd, NULL, 0, NULL, 0);
+	if (r == 0)
+		card_blocked = blocked;
+
+	return r;
 }
 
 static const struct rfkill_ops rfkill_ops = {