netdev - [PATCH (net.git) 2/6] stmmac: fix and better tune the default buffer sizes

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Date:	Wed, 26 Feb 2014 09:01:03 +0100
From:	Giuseppe Cavallaro <peppe.cavallaro@...com>
To:	<netdev@...r.kernel.org>
Cc:	Giuseppe Cavallaro <peppe.cavallaro@...com>
Subject: [PATCH (net.git) 2/6] stmmac: fix and better tune the default buffer sizes

This patch is to fix and tune the default buffer sizes.
It reduces the default bufsize used by the driver from
2048 to 1518 (taking into account the extra 4 bytes in case of VLAN).

Patch has been tested on both ARM and SH4 platform based.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@...com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |   16 ++++++++++------
 1 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b418f94..40d811d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -92,8 +92,12 @@ static int tc = TC_DEFAULT;
 module_param(tc, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(tc, "DMA threshold control value");
 
-#define DMA_BUFFER_SIZE	BUF_SIZE_4KiB
-static int buf_sz = DMA_BUFFER_SIZE;
+#ifdef STMMAC_VLAN_TAG_USED
+#define	DEFAULT_BUFSIZE	(VLAN_ETH_FRAME_LEN + ETH_FCS_LEN)
+#else
+#define	DEFAULT_BUFSIZE	(ETH_FRAME_LEN + ETH_FCS_LEN)
+#endif
+static int buf_sz = DEFAULT_BUFSIZE;
 module_param(buf_sz, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(buf_sz, "DMA buffer size");
 
@@ -136,8 +140,8 @@ static void stmmac_verify_args(void)
 		dma_rxsize = DMA_RX_SIZE;
 	if (unlikely(dma_txsize < 0))
 		dma_txsize = DMA_TX_SIZE;
-	if (unlikely((buf_sz < DMA_BUFFER_SIZE) || (buf_sz > BUF_SIZE_16KiB)))
-		buf_sz = DMA_BUFFER_SIZE;
+	if (unlikely((buf_sz < DEFAULT_BUFSIZE) || (buf_sz > BUF_SIZE_16KiB)))
+		buf_sz = DEFAULT_BUFSIZE;
 	if (unlikely(flow_ctrl > 1))
 		flow_ctrl = FLOW_AUTO;
 	else if (likely(flow_ctrl < 0))
@@ -901,10 +905,10 @@ static int stmmac_set_bfsize(int mtu, int bufsize)
 		ret = BUF_SIZE_8KiB;
 	else if (mtu >= BUF_SIZE_2KiB)
 		ret = BUF_SIZE_4KiB;
-	else if (mtu >= DMA_BUFFER_SIZE)
+	else if (mtu > DEFAULT_BUFSIZE)
 		ret = BUF_SIZE_2KiB;
 	else
-		ret = DMA_BUFFER_SIZE;
+		ret = DEFAULT_BUFSIZE;
 
 	return ret;
 }
-- 
1.7.4.4

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