[PATCH net-next v2 07/15] net: stmmac: remove rx_tail_addr

[Russell King (Oracle)]

There is only one place where rx_q->rx_tail_addr is used - the new
stmmac_set_queue_rx_tail_ptr(). Make this a local variable and remove
it from struct stmmac_rx_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_rx_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.

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 | 5 +++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index b096a9e090e3..d1f8383d1c04 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -131,7 +131,6 @@ struct stmmac_rx_queue {
 	unsigned int buf_alloc_num;
 	unsigned int napi_skb_frag_size;
 	dma_addr_t dma_rx_phy;
-	u32 rx_tail_addr;
 	unsigned int state_saved;
 	struct {
 		struct sk_buff *skb;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 8823f8f5b053..1d40168ec68d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -388,8 +388,9 @@ static void stmmac_set_queue_rx_tail_ptr(struct stmmac_priv *priv,
 	 * descriptiors are only supported with dwmac1000 (<v4.0) which
 	 * does not implement .set_rx_tail_ptr
 	 */
-	rx_q->rx_tail_addr = rx_q->dma_rx_phy + index * sizeof(struct dma_desc);
-	stmmac_set_rx_tail_ptr(priv, priv->ioaddr, rx_q->rx_tail_addr, chan);
+	u32 rx_tail_addr = rx_q->dma_rx_phy + index * sizeof(struct dma_desc);
+
+	stmmac_set_rx_tail_ptr(priv, priv->ioaddr, rx_tail_addr, chan);
 }
 
 /**
-- 
2.47.3