r8169: replace rx_buf_sz with a constant

rx_buf_sz is constant, so we don't have to pass it as parameter and
in general can replace it with a constant.

When working on this I noticed that also before in
rtl_set_rx_max_size() a value of 0x4000 is set, what is not in line
with the chip spec. According to the spec only bits 0..13 are used
and we set an effective value of zero therefore.
However, the driver still seems to work and due to potential side
effects I'm reluctant to make a change.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -88,6 +88,7 @@ static const int multicast_filter_limit = 32;
 #define InterFrameGap	0x03	/* 3 means InterFrameGap = the shortest one */
 
 #define R8169_REGS_SIZE		256
+#define R8169_RX_BUF_SIZE	(SZ_16K - 1)
 #define NUM_TX_DESC	64	/* Number of Tx descriptor registers */
 #define NUM_RX_DESC	256U	/* Number of Rx descriptor registers */
 #define R8169_TX_RING_BYTES	(NUM_TX_DESC * sizeof(struct TxDesc))
@@ -343,7 +344,6 @@ static const struct pci_device_id rtl8169_pci_tbl[] = {
 
 MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);
 
-static int rx_buf_sz = 16383;
 static int use_dac = -1;
 static struct {
 	u32 msg_enable;
@@ -5385,10 +5385,10 @@ static u16 rtl_rw_cpluscmd(struct rtl8169_private *tp)
 	return cmd;
 }
 
-static void rtl_set_rx_max_size(struct rtl8169_private *tp, unsigned int rx_buf_sz)
+static void rtl_set_rx_max_size(struct rtl8169_private *tp)
 {
 	/* Low hurts. Let's disable the filtering. */
-	RTL_W16(tp, RxMaxSize, rx_buf_sz + 1);
+	RTL_W16(tp, RxMaxSize, R8169_RX_BUF_SIZE + 1);
 }
 
 static void rtl8169_set_magic_reg(struct rtl8169_private *tp, unsigned mac_version)
@@ -5489,7 +5489,7 @@ static void rtl_hw_start_8169(struct net_device *dev)
 
 	RTL_W8(tp, EarlyTxThres, NoEarlyTx);
 
-	rtl_set_rx_max_size(tp, rx_buf_sz);
+	rtl_set_rx_max_size(tp);
 
 	if (tp->mac_version == RTL_GIGA_MAC_VER_01 ||
 	    tp->mac_version == RTL_GIGA_MAC_VER_02 ||
@@ -6329,7 +6329,7 @@ static void rtl_hw_start_8168(struct net_device *dev)
 
 	RTL_W8(tp, MaxTxPacketSize, TxPacketMax);
 
-	rtl_set_rx_max_size(tp, rx_buf_sz);
+	rtl_set_rx_max_size(tp);
 
 	tp->cp_cmd |= RTL_R16(tp, CPlusCmd) | PktCntrDisable | INTT_1;
 
@@ -6613,7 +6613,7 @@ static void rtl_hw_start_8101(struct net_device *dev)
 
 	RTL_W8(tp, MaxTxPacketSize, TxPacketMax);
 
-	rtl_set_rx_max_size(tp, rx_buf_sz);
+	rtl_set_rx_max_size(tp);
 
 	tp->cp_cmd &= ~R810X_CPCMD_QUIRK_MASK;
 	RTL_W16(tp, CPlusCmd, tp->cp_cmd);
@@ -6695,29 +6695,28 @@ static inline void rtl8169_make_unusable_by_asic(struct RxDesc *desc)
 static void rtl8169_free_rx_databuff(struct rtl8169_private *tp,
 				     void **data_buff, struct RxDesc *desc)
 {
-	dma_unmap_single(tp_to_dev(tp), le64_to_cpu(desc->addr), rx_buf_sz,
-			 DMA_FROM_DEVICE);
+	dma_unmap_single(tp_to_dev(tp), le64_to_cpu(desc->addr),
+			 R8169_RX_BUF_SIZE, DMA_FROM_DEVICE);
 
 	kfree(*data_buff);
 	*data_buff = NULL;
 	rtl8169_make_unusable_by_asic(desc);
 }
 
-static inline void rtl8169_mark_to_asic(struct RxDesc *desc, u32 rx_buf_sz)
+static inline void rtl8169_mark_to_asic(struct RxDesc *desc)
 {
 	u32 eor = le32_to_cpu(desc->opts1) & RingEnd;
 
 	/* Force memory writes to complete before releasing descriptor */
 	dma_wmb();
 
-	desc->opts1 = cpu_to_le32(DescOwn | eor | rx_buf_sz);
+	desc->opts1 = cpu_to_le32(DescOwn | eor | R8169_RX_BUF_SIZE);
 }
 
-static inline void rtl8169_map_to_asic(struct RxDesc *desc, dma_addr_t mapping,
-				       u32 rx_buf_sz)
+static inline void rtl8169_map_to_asic(struct RxDesc *desc, dma_addr_t mapping)
 {
 	desc->addr = cpu_to_le64(mapping);
-	rtl8169_mark_to_asic(desc, rx_buf_sz);
+	rtl8169_mark_to_asic(desc);
 }
 
 static inline void *rtl8169_align(void *data)
@@ -6733,18 +6732,18 @@ static struct sk_buff *rtl8169_alloc_rx_data(struct rtl8169_private *tp,
 	struct device *d = tp_to_dev(tp);
 	int node = dev_to_node(d);
 
-	data = kmalloc_node(rx_buf_sz, GFP_KERNEL, node);
+	data = kmalloc_node(R8169_RX_BUF_SIZE, GFP_KERNEL, node);
 	if (!data)
 		return NULL;
 
 	if (rtl8169_align(data) != data) {
 		kfree(data);
-		data = kmalloc_node(rx_buf_sz + 15, GFP_KERNEL, node);
+		data = kmalloc_node(R8169_RX_BUF_SIZE + 15, GFP_KERNEL, node);
 		if (!data)
 			return NULL;
 	}
 
-	mapping = dma_map_single(d, rtl8169_align(data), rx_buf_sz,
+	mapping = dma_map_single(d, rtl8169_align(data), R8169_RX_BUF_SIZE,
 				 DMA_FROM_DEVICE);
 	if (unlikely(dma_mapping_error(d, mapping))) {
 		if (net_ratelimit())
@@ -6752,7 +6751,7 @@ static struct sk_buff *rtl8169_alloc_rx_data(struct rtl8169_private *tp,
 		goto err_out;
 	}
 
-	rtl8169_map_to_asic(desc, mapping, rx_buf_sz);
+	rtl8169_map_to_asic(desc, mapping);
 	return data;
 
 err_out:
@@ -6864,7 +6863,7 @@ static void rtl_reset_work(struct rtl8169_private *tp)
 	rtl8169_hw_reset(tp);
 
 	for (i = 0; i < NUM_RX_DESC; i++)
-		rtl8169_mark_to_asic(tp->RxDescArray + i, rx_buf_sz);
+		rtl8169_mark_to_asic(tp->RxDescArray + i);
 
 	rtl8169_tx_clear(tp);
 	rtl8169_init_ring_indexes(tp);
@@ -7444,7 +7443,7 @@ process_pkt:
 		}
 release_descriptor:
 		desc->opts2 = 0;
-		rtl8169_mark_to_asic(desc, rx_buf_sz);
+		rtl8169_mark_to_asic(desc);
 	}
 
 	count = cur_rx - tp->cur_rx;