From: Troy Kisky <troy.ki...@boundarydevices.com> Sent: Thursday, February 25,
2016 8:37 AM
> To: netdev@vger.kernel.org; da...@davemloft.net; b38...@freescale.com
> Cc: fabio.este...@freescale.com; l.st...@pengutronix.de; and...@lunn.ch;
> trem...@gmail.com; li...@arm.linux.org.uk; linux-arm-
> ker...@lists.infradead.org; l...@boundarydevices.com; shawn...@kernel.org;
> johan...@sipsolutions.net; stillcompil...@gmail.com;
> sergei.shtyl...@cogentembedded.com; a...@arndb.de; Troy Kisky
> <troy.ki...@boundarydevices.com>
> Subject: [PATCH net-next V2 07/16] net: fec: set cbd_sc without relying on
> previous value
>
> Relying on the wrap bit to stay valid once initialized when the controller
> also
> writes to this byte seems undesirable since we can easily know what the value
> should be.
>
> Signed-off-by: Troy Kisky <troy.ki...@boundarydevices.com>
> ---
> drivers/net/ethernet/freescale/fec_main.c | 38
> +++++++++----------------------
> 1 file changed, 11 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index 791f385..6ceb5f9 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -340,9 +340,8 @@ fec_enet_txq_submit_frag_skb(struct
> fec_enet_priv_tx_q *txq,
> bdp = fec_enet_get_nextdesc(bdp, &txq->bd);
> ebdp = (struct bufdesc_ex *)bdp;
>
> - status = fec16_to_cpu(bdp->cbd_sc);
> - status &= ~BD_ENET_TX_STATS;
> - status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);
> + status = BD_ENET_TX_TC | BD_ENET_TX_READY |
> + ((bdp == txq->bd.last) ? BD_SC_WRAP : 0);
> frag_len = skb_shinfo(skb)->frags[frag].size;
>
> /* Handle the last BD specially */
> @@ -436,8 +435,6 @@ static int fec_enet_txq_submit_skb(struct
> fec_enet_priv_tx_q *txq,
> /* Fill in a Tx ring entry */
> bdp = txq->bd.cur;
> last_bdp = bdp;
> - status = fec16_to_cpu(bdp->cbd_sc);
> - status &= ~BD_ENET_TX_STATS;
>
> /* Set buffer length and buffer pointer */
> bufaddr = skb->data;
> @@ -462,6 +459,8 @@ static int fec_enet_txq_submit_skb(struct
> fec_enet_priv_tx_q *txq,
> return NETDEV_TX_OK;
> }
>
> + status = BD_ENET_TX_TC | BD_ENET_TX_READY |
> + ((bdp == txq->bd.last) ? BD_SC_WRAP : 0);
> if (nr_frags) {
> last_bdp = fec_enet_txq_submit_frag_skb(txq, skb, ndev);
> if (IS_ERR(last_bdp)) {
> @@ -512,7 +511,6 @@ static int fec_enet_txq_submit_skb(struct
> fec_enet_priv_tx_q *txq,
> /* Send it on its way. Tell FEC it's ready, interrupt when done,
> * it's the last BD of the frame, and to put the CRC on the end.
> */
> - status |= (BD_ENET_TX_READY | BD_ENET_TX_TC);
This is completely error. We have to prepare all BDs for frag skb, and then
enable "READY" and "TC" bit for the first BD, otherwise uDMA copy un-correct
data to fifo.
<snip>
