[PATCH net-next v4 14/15] net: stmmac: remove tx_tail_addr

[Russell King (Oracle)]

There is only one place where tx_q->tx_tail_addr is used - the new
stmmac_set_queue_tx_tail_ptr(). Make this a local variable and remove
it from struct stmmac_tx_queue.

This commit does not change the semantics - the hardware relies upon
the descriptor ring not crossing a 4GiB boundary as the high address
bits are programmed into a separate register via stmmac_init_tx_chan().
Hence, truncating the DMA address to 32-bit is fine as the register it
will be programmed into is 32-bit, and the high bits are handled
elsewhere.

Also change the type of desc_size to size_t, as this variable is
initialised from sizeof().

Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h      | 1 -
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 7 ++++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index d1f8383d1c04..7cc5967aecd7 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -79,7 +79,6 @@ struct stmmac_tx_queue {
 	unsigned int cur_tx;
 	unsigned int dirty_tx;
 	dma_addr_t dma_tx_phy;
-	dma_addr_t tx_tail_addr;
 	u32 mss;
 };
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 4521469c5e1d..55b79e9e637f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -389,12 +389,13 @@ static void stmmac_set_queue_tx_tail_ptr(struct stmmac_priv *priv,
 					 struct stmmac_tx_queue *tx_q,
 					 unsigned int chan, unsigned int index)
 {
-	int desc_size;
+	size_t desc_size;
+	u32 tx_tail_addr;
 
 	desc_size = stmmac_get_tx_desc_size(priv, tx_q);
 
-	tx_q->tx_tail_addr = tx_q->dma_tx_phy + index * desc_size;
-	stmmac_set_tx_tail_ptr(priv, priv->ioaddr, tx_q->tx_tail_addr, chan);
+	tx_tail_addr = tx_q->dma_tx_phy + index * desc_size;
+	stmmac_set_tx_tail_ptr(priv, priv->ioaddr, tx_tail_addr, chan);
 }
 
 static size_t stmmac_get_rx_desc_size(struct stmmac_priv *priv)
-- 
2.47.3