[PATCH v4 1/2] net: moxa: clear TX descriptor length bits

[jonas.jensen@gmail.com (Jonas Jensen)]

TX buffer length is not cleared on ndo_start_xmit().
Failing to do so can bug/hang the controller and
cause TX interrupts to stop altogether.

Add TX_DESC1_BUF_SIZE_MASK to bits that are cleared,
before the TX buffer length is set.

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=69031

Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
---

Notes:
    Changes since v3:
    
    1. commit message reworded
    
    Applies to next-20140818

 drivers/net/ethernet/moxa/moxart_ether.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c
index 5020fd4..aa45607 100644
--- a/drivers/net/ethernet/moxa/moxart_ether.c
+++ b/drivers/net/ethernet/moxa/moxart_ether.c
@@ -348,7 +348,8 @@ static int moxart_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 
 	txdes1 = readl(desc + TX_REG_OFFSET_DESC1);
 	txdes1 |= TX_DESC1_LTS | TX_DESC1_FTS;
-	txdes1 &= ~(TX_DESC1_FIFO_COMPLETE | TX_DESC1_INTR_COMPLETE);
+	txdes1 &= ~(TX_DESC1_FIFO_COMPLETE | TX_DESC1_INTR_COMPLETE |
+		    TX_DESC1_BUF_SIZE_MASK);
 	txdes1 |= (len & TX_DESC1_BUF_SIZE_MASK);
 	writel(txdes1, desc + TX_REG_OFFSET_DESC1);
 	writel(TX_DESC0_DMA_OWN, desc + TX_REG_OFFSET_DESC0);
-- 
1.8.2.1