[RFC PATCH 4/6] net: ethernet: ti: am65-cpsw-nuss: Do not set buf_type for SKB fragments

[Siddharth Vadapalli]

There are two kinds of descriptors:
1. Host Packet Descriptor
2. Host Buffer Descriptor

Unfragmented SKBs are always associated with a single Host Packet
Descriptor. Fragmented SKBs on the other hand have the Start-of-Packet
SKB associated with a single Host Packet Descriptor and the remaining
fragments are associated with a Host Buffer Descriptor. A single Host
Packet Descriptor is linked to a chain of Host Buffer Descriptors for
fragmented SKBs with as many Host Buffer Descriptors as the number of
SKB fragments.

Since packet completion handling only uses the buffer type of the Host
Packet Descriptor, setting the buffer type of the linked Host Buffer
Descriptors is an unnecessary operation which wastes CPU cycles per SKB
fragment.

Hence, do not set buffer type for SKB fragments.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
---
 drivers/net/ethernet/ti/am65-cpsw-nuss.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
index d9400599e80a..6df6cb52d952 100644
--- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c
@@ -1678,9 +1678,6 @@ static netdev_tx_t am65_cpsw_nuss_ndo_slave_xmit(struct sk_buff *skb,
 			goto busy_free_descs;
 		}
 
-		am65_cpsw_nuss_set_buf_type(tx_chn, next_desc,
-					    AM65_CPSW_TX_BUF_TYPE_SKB);
-
 		buf_dma = skb_frag_dma_map(tx_chn->dma_dev, frag, 0, frag_size,
 					   DMA_TO_DEVICE);
 		if (unlikely(dma_mapping_error(tx_chn->dma_dev, buf_dma))) {
-- 
2.51.1