[PATCH net-next V3 08/16] net: fec: set cbd_sc without relying on previous value

[Fugang Duan]

From: Troy Kisky <troy.kisky at boundarydevices.com> Sent: Wednesday, April 06, 2016 10:26 AM
> To: netdev at vger.kernel.org; davem at davemloft.net; Fugang Duan
> <fugang.duan at nxp.com>; lznuaa at gmail.com
> Cc: Fabio Estevam <fabio.estevam at nxp.com>; l.stach at pengutronix.de;
> andrew at lunn.ch; tremyfr at gmail.com; gerg at uclinux.org; linux-arm-
> kernel at lists.infradead.org; johannes at sipsolutions.net;
> stillcompiling at gmail.com; sergei.shtylyov at cogentembedded.com;
> arnd at arndb.de; Troy Kisky <troy.kisky at boundarydevices.com>
> Subject: [PATCH net-next V3 08/16] net: fec: set cbd_sc without relying on
> previous value
> 
> Relying on the wrap bit of cdb_sc 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.kisky at boundarydevices.com>
> 
> ---
> v3: change commit message
> ---
>  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 3cd0cdf..21d2cd0 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);
>  	bdp->cbd_sc = cpu_to_fec16(status);
> 
>  	/* If this was the last BD in the ring, start at the beginning again. */ @@ -
> 544,11 +542,6 @@ fec_enet_txq_put_data_tso(struct fec_enet_priv_tx_q *txq,
> struct sk_buff *skb,
>  	unsigned int estatus = 0;
>  	dma_addr_t addr;
> 
> -	status = fec16_to_cpu(bdp->cbd_sc);
> -	status &= ~BD_ENET_TX_STATS;
> -
> -	status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);
> -
>  	if (((unsigned long) data) & fep->tx_align ||
>  		fep->quirks & FEC_QUIRK_SWAP_FRAME) {
>  		memcpy(txq->tx_bounce[index], data, size); @@ -578,15
> +571,16 @@ fec_enet_txq_put_data_tso(struct fec_enet_priv_tx_q *txq,
> struct sk_buff *skb,
>  		ebdp->cbd_esc = cpu_to_fec32(estatus);
>  	}
> 
> +	status = BD_ENET_TX_TC | BD_ENET_TX_READY |
> +			((bdp == txq->bd.last) ? BD_SC_WRAP : 0);
>  	/* Handle the last BD specially */
>  	if (last_tcp)
> -		status |= (BD_ENET_TX_LAST | BD_ENET_TX_TC);
> +		status |= BD_ENET_TX_LAST;
>  	if (is_last) {
>  		status |= BD_ENET_TX_INTR;
>  		if (fep->bufdesc_ex)
>  			ebdp->cbd_esc |= cpu_to_fec32(BD_ENET_TX_INT);
>  	}
> -
>  	bdp->cbd_sc = cpu_to_fec16(status);
> 
>  	return 0;
> @@ -602,13 +596,8 @@ fec_enet_txq_put_hdr_tso(struct fec_enet_priv_tx_q
> *txq,
>  	struct bufdesc_ex *ebdp = container_of(bdp, struct bufdesc_ex, desc);
>  	void *bufaddr;
>  	unsigned long dmabuf;
> -	unsigned short status;
>  	unsigned int estatus = 0;
> 
> -	status = fec16_to_cpu(bdp->cbd_sc);
> -	status &= ~BD_ENET_TX_STATS;
> -	status |= (BD_ENET_TX_TC | BD_ENET_TX_READY);
> -
>  	bufaddr = txq->tso_hdrs + index * TSO_HEADER_SIZE;
>  	dmabuf = txq->tso_hdrs_dma + index * TSO_HEADER_SIZE;
>  	if (((unsigned long)bufaddr) & fep->tx_align || @@ -641,8 +630,8 @@
> fec_enet_txq_put_hdr_tso(struct fec_enet_priv_tx_q *txq,
>  		ebdp->cbd_esc = cpu_to_fec32(estatus);
>  	}
> 
> -	bdp->cbd_sc = cpu_to_fec16(status);
> -
> +	bdp->cbd_sc = cpu_to_fec16(BD_ENET_TX_TC | BD_ENET_TX_READY |
> +			((bdp == txq->bd.last) ? BD_SC_WRAP : 0));
>  	return 0;
>  }
> 
> @@ -1454,12 +1443,6 @@ static int fec_rxq(struct net_device *ndev, struct
> fec_enet_priv_rx_q *rxq,
>  		}
> 
>  rx_processing_done:
> -		/* Clear the status flags for this buffer */
> -		status &= ~BD_ENET_RX_STATS;
> -
> -		/* Mark the buffer empty */
> -		status |= BD_ENET_RX_EMPTY;
> -
>  		if (fep->bufdesc_ex) {
>  			struct bufdesc_ex *ebdp = (struct bufdesc_ex *)bdp;
> 
> @@ -1471,7 +1454,8 @@ rx_processing_done:
>  		 * performed before transferring ownership.
>  		 */
>  		wmb();
> -		bdp->cbd_sc = cpu_to_fec16(status);
> +		bdp->cbd_sc = cpu_to_fec16(BD_ENET_RX_EMPTY |
> +				((bdp == rxq->bd.last) ? BD_SC_WRAP : 0));
> 
>  		/* Update BD pointer to next entry */
>  		bdp = fec_enet_get_nextdesc(bdp, &rxq->bd);
> --
> 2.5.0


Patch 08 ~ 16:  Acked-by: Fugang Duan <fugang.duan at nxp.com>