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sky2: enforce minimum ring size

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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>
This commit is contained in:
stephen hemminger 2011-11-17 14:37:23 +00:00 committed by David S. Miller
parent 4a8bb7e27f
commit 738a849c8e
1 changed files with 12 additions and 2 deletions
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14
drivers/net/ethernet/marvell/sky2.c
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@ -4088,6 +4088,16 @@ static int sky2_set_coalesce(struct net_device *dev,
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 @@ static int sky2_set_ringparam(struct net_device *dev,
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 @@ static __devinit struct net_device *sky2_init_netdev(struct sky2_hw *hw,
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;