sky2: enforce minimum ring size
The hardware has a restriction that the minimum ring size possible
is 128. The number of elements used is controlled by tx_pending and
the overall number of elements in the ring tx_ring_size, therefore it
is okay to limit the number of elements in use to a small value (63)
but still provide a bigger ring.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c
index 539de09..d996871 100644
--- a/drivers/net/ethernet/marvell/sky2.c
+++ b/drivers/net/ethernet/marvell/sky2.c
@@ -4088,6 +4088,16 @@
return 0;
}
+/*
+ * Hardware is limited to min of 128 and max of 2048 for ring size
+ * and rounded up to next power of two
+ * to avoid division in modulus calclation
+ */
+static unsigned long roundup_ring_size(unsigned long pending)
+{
+ return max(128ul, roundup_pow_of_two(pending+1));
+}
+
static void sky2_get_ringparam(struct net_device *dev,
struct ethtool_ringparam *ering)
{
@@ -4115,7 +4125,7 @@
sky2->rx_pending = ering->rx_pending;
sky2->tx_pending = ering->tx_pending;
- sky2->tx_ring_size = roundup_pow_of_two(sky2->tx_pending+1);
+ sky2->tx_ring_size = roundup_ring_size(sky2->tx_pending);
return sky2_reattach(dev);
}
@@ -4709,7 +4719,7 @@
spin_lock_init(&sky2->phy_lock);
sky2->tx_pending = TX_DEF_PENDING;
- sky2->tx_ring_size = roundup_pow_of_two(TX_DEF_PENDING+1);
+ sky2->tx_ring_size = roundup_ring_size(TX_DEF_PENDING);
sky2->rx_pending = RX_DEF_PENDING;
hw->dev[port] = dev;