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net: bcmgenet: simplify circular pointer arithmetic

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A 2's complement subtraction will always do a borrow, so masking
off the sign bits is the same as conditionally adding (mask+1).

Signed-off-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Doug Berger 2017-03-13 17:41:33 -07:00 committed by David S. Miller
parent 83ee102a69
commit c298ede2fe
1 changed files with 5 additions and 14 deletions
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19
drivers/net/ethernet/broadcom/genet/bcmgenet.c
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@ -1,7 +1,7 @@
/*
* Broadcom GENET (Gigabit Ethernet) controller driver
*
* Copyright (c) 2014 Broadcom Corporation
* Copyright (c) 2014-2017 Broadcom
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
@ -1175,13 +1175,9 @@ static unsigned int __bcmgenet_tx_reclaim(struct net_device *dev,
unsigned int txbds_processed = 0;
/* Compute how many buffers are transmitted since last xmit call */
c_index = bcmgenet_tdma_ring_readl(priv, ring->index, TDMA_CONS_INDEX);
c_index &= DMA_C_INDEX_MASK;
if (likely(c_index >= ring->c_index))
txbds_ready = c_index - ring->c_index;
else
txbds_ready = (DMA_C_INDEX_MASK + 1) - ring->c_index + c_index;
c_index = bcmgenet_tdma_ring_readl(priv, ring->index, TDMA_CONS_INDEX)
& DMA_C_INDEX_MASK;
txbds_ready = (c_index - ring->c_index) & DMA_C_INDEX_MASK;
netif_dbg(priv, tx_done, dev,
"%s ring=%d old_c_index=%u c_index=%u txbds_ready=%u\n",
@ -1611,12 +1607,7 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_rx_ring *ring,
}
p_index &= DMA_P_INDEX_MASK;
if (likely(p_index >= ring->c_index))
rxpkttoprocess = p_index - ring->c_index;
else
rxpkttoprocess = (DMA_C_INDEX_MASK + 1) - ring->c_index +
p_index;
rxpkttoprocess = (p_index - ring->c_index) & DMA_C_INDEX_MASK;
netif_dbg(priv, rx_status, dev,
"RDMA: rxpkttoprocess=%d\n", rxpkttoprocess);