From mboxrd@z Thu Jan 1 00:00:00 1970 From: troy.kisky@boundarydevices.com (Troy Kisky) Date: Fri, 4 Mar 2016 09:08:07 -0700 Subject: [PATCH net-next V2 07/16] net: fec: set cbd_sc without relying on previous value In-Reply-To: References: <1456360619-24390-1-git-send-email-troy.kisky@boundarydevices.com> <1456360619-24390-8-git-send-email-troy.kisky@boundarydevices.com> Message-ID: <56D9B2E7.6050000@boundarydevices.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 3/4/2016 2:29 AM, Fugang Duan wrote: > From: Troy Kisky Sent: Thursday, February 25, 2016 8:37 AM >> To: netdev at vger.kernel.org; davem at davemloft.net; b38611 at freescale.com >> Cc: fabio.estevam at freescale.com; l.stach at pengutronix.de; andrew at lunn.ch; >> tremyfr at gmail.com; linux at arm.linux.org.uk; linux-arm- >> kernel at lists.infradead.org; laci at boundarydevices.com; shawnguo at kernel.org; >> johannes at sipsolutions.net; stillcompiling at gmail.com; >> sergei.shtylyov at cogentembedded.com; arnd at arndb.de; Troy Kisky >> >> 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 >> --- >> 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