For addressing 4 bytes alignment restriction on transmission
buffer for R-Car Gen2 we use 2 descriptors whereas it is a single
descriptor for other cases.
Replace the macros NUM_TX_DESC_GEN[23] with magic number and
add a comment to explain it.
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Suggested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
drivers/net/ethernet/renesas/ravb.h | 4 ----
drivers/net/ethernet/renesas/ravb_main.c | 8 ++++++--
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 37ad0f8aaf3c..84700a82a41c 100644
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -956,10 +956,6 @@ enum RAVB_QUEUE {
#define RX_BUF_SZ (2048 - ETH_FCS_LEN + sizeof(__sum16))
-/* TX descriptors per packet */
-#define NUM_TX_DESC_GEN2 2
-#define NUM_TX_DESC_GEN3 1
-
struct ravb_tstamp_skb {
struct list_head list;
struct sk_buff *skb;
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 02842b980a7f..073e690ab830 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2160,8 +2160,12 @@ static int ravb_probe(struct platform_device *pdev)
ndev->max_mtu = 2048 - (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN);
ndev->min_mtu = ETH_MIN_MTU;
- priv->num_tx_desc = info->aligned_tx ?
- NUM_TX_DESC_GEN2 : NUM_TX_DESC_GEN3;
+ /* FIXME: R-Car Gen2 has 4byte alignment restriction for tx buffer
+ * Use two descriptor to handle such situation. First descriptor to
+ * handle aligned data buffer and second descriptor to handle the
+ * overflow data because of alignment.
+ */
+ priv->num_tx_desc = info->aligned_tx ? 2 : 1;
/* Set function */
ndev->netdev_ops = &ravb_netdev_ops;
--
2.17.1
