net: dsa: hellcreek: Adjust schedule look ahead window

Traffic schedules can only be started up to eight seconds within the
future. Therefore, the driver periodically checks every two seconds whether the
admin base time provided by the user is inside that window. If so the schedule
is started. Otherwise the check is deferred.

However, according to the programming manual the look ahead window size should
be four - not eight - seconds. By using the proposed value of four seconds
starting a schedule at a specified admin base time actually works as expected.

Fixes: 24dfc6eb39b2 ("net: dsa: hellcreek: Add TAPRIO offloading support")
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/hirschmann/hellcreek.c b/drivers/net/dsa/hirschmann/hellcreek.c
index b57aea92684b87734d652ec997c9562525c85997..7062db6a083c2ba616ba44e723ba5858af33c93a 100644 (file)
--- a/drivers/net/dsa/hirschmann/hellcreek.c
+++ b/drivers/net/dsa/hirschmann/hellcreek.c
@@ -1550,7 +1550,7 @@ static bool hellcreek_schedule_startable(struct hellcreek *hellcreek, int port)
        /* Calculate difference to admin base time */
        base_time_ns = ktime_to_ns(hellcreek_port->current_schedule->base_time);
 
-       return base_time_ns - current_ns < (s64)8 * NSEC_PER_SEC;
+       return base_time_ns - current_ns < (s64)4 * NSEC_PER_SEC;
 }
 
 static void hellcreek_start_schedule(struct hellcreek *hellcreek, int port)