[PATCH] sis190: the size of the Rx buffer is constrained

Add a restriction to the size of the Rx buffer

SiS driver forces the size of any Rx buffer to be a multiple of 64 bit.
I would not be surprized that it goes along with some alignment issues
which have been experienced before. So far it does not make much of a
difference (both drivers use 1536 bytes buffer).

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

diff --git a/drivers/net/sis190.c b/drivers/net/sis190.c
index 1e8e7111c261f2955374dd41a8c3e3fb19cd30bc..2229698debbd11d02052573e28d6c14241d3f4db 100644 (file)
--- a/drivers/net/sis190.c
+++ b/drivers/net/sis190.c
@@ -69,6 +69,7 @@
 #define TX_RING_BYTES          (NUM_TX_DESC * sizeof(struct TxDesc))
 #define RX_RING_BYTES          (NUM_RX_DESC * sizeof(struct RxDesc))
 #define RX_BUF_SIZE            1536
+#define RX_BUF_MASK            0xfff8
 
 #define SIS190_REGS_SIZE       0x80
 #define SIS190_TX_TIMEOUT      (6*HZ)
@@ -400,7 +401,7 @@ static inline void sis190_give_to_asic(struct RxDesc *desc, u32 rx_buf_sz)
        u32 eor = le32_to_cpu(desc->size) & RingEnd;
 
        desc->PSize = 0x0;
-       desc->size = cpu_to_le32(rx_buf_sz | eor);
+       desc->size = cpu_to_le32((rx_buf_sz & RX_BUF_MASK) | eor);
        wmb();
        desc->status = cpu_to_le32(OWNbit | INTbit);
 }
@@ -924,6 +925,11 @@ static void sis190_set_rxbufsize(struct sis190_private *tp,
        unsigned int mtu = dev->mtu;
 
        tp->rx_buf_sz = (mtu > RX_BUF_SIZE) ? mtu + ETH_HLEN + 8 : RX_BUF_SIZE;
+       /* RxDesc->size has a licence to kill the lower bits */
+       if (tp->rx_buf_sz & 0x07) {
+               tp->rx_buf_sz += 8;
+               tp->rx_buf_sz &= RX_BUF_MASK;
+       }
 }
 
 static int sis190_open(struct net_device *dev)