[PATCH] net: altera_tse: fix msgdma_tx_completion on non-zero fill_level case

[Atsushi Nemoto]

From: Tomonori Sakita <tomonori.sak...@sord.co.jp>

If fill_level was not zero and status was not BUSY,
result of "tx_prod - tx_cons - inuse" might be zero.
Subtracting 1 unconditionally results invalid negative return value
on this case.
The subtraction is not needed if fill_level was not zero.

Signed-off-by: Tomonori Sakita <tomonori.sak...@sord.co.jp>
Signed-off-by: Atsushi Nemoto <atsushi.nem...@sord.co.jp>
---
 drivers/net/ethernet/altera/altera_msgdma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/altera/altera_msgdma.c 
b/drivers/net/ethernet/altera/altera_msgdma.c
index 0fb986b..3df73d3 100644
--- a/drivers/net/ethernet/altera/altera_msgdma.c
+++ b/drivers/net/ethernet/altera/altera_msgdma.c
@@ -145,7 +145,7 @@ u32 msgdma_tx_completions(struct altera_tse_private *priv)
                        & 0xffff;
 
        if (inuse) { /* Tx FIFO is not empty */
-               ready = priv->tx_prod - priv->tx_cons - inuse - 1;
+               ready = priv->tx_prod - priv->tx_cons - inuse;
        } else {
                /* Check for buffered last packet */
                status = csrrd32(priv->tx_dma_csr, msgdma_csroffs(status));
-- 
2.1.4