On 3/4/2016 2:29 AM, Fugang Duan wrote:
> 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.
>
I don't follow. Please read patch again.
Thanks
Troy
