Subject: RE: [PATCH V7 3/7] net: sxgbe: add TSO support for Samsung sxgbe

From: Byungho An <[email-masked]>
Date: Thu, 20 Mar 2014 09:56:56 -0700

Rayagond Kokatanur <[email-masked]> wrote :
> On Thu, Mar 20, 2014 at 7:56 AM, Byungho An <[email-masked]> wrote:
> > From: Vipul Pandya <[email-masked]>
> >
> > Enable TSO during initialization for each DMA channels
> >
> > Signed-off-by: Vipul Pandya <[email-masked]>
> > Neatening-by: Joe Perches <[email-masked]>
> > Signed-off-by: Byungho An <[email-masked]>
> > ---
> >  drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h |    1 +
> >  drivers/net/ethernet/samsung/sxgbe/sxgbe_desc.h   |   17 +++--
> >  drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.c    |   10 +++
> >  drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.h    |    2 +
> >  drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c   |   81
> +++++++++++++++++++--
> >  5 files changed, 98 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
> > b/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
> > index 587b691..f8ba7e4 100644
> > --- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
> > +++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
> > @@ -327,6 +327,7 @@ struct sxgbe_tx_queue {
> >         u32 tx_coal_frames;
> >         u32 tx_coal_timer;
> >         int hwts_tx_en;
> > +       u16 prev_mss;
> >         u8 queue_no;
> >  };
> >
> > diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_desc.h
> > b/drivers/net/ethernet/samsung/sxgbe/sxgbe_desc.h
> > index 41844d4..547edf3 100644
> > --- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_desc.h
> > +++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_desc.h
> > @@ -167,8 +167,9 @@ struct sxgbe_desc_ops {
> >         void (*init_tx_desc)(struct sxgbe_tx_norm_desc *p);
> >
> >         /* Invoked by the xmit function to prepare the tx descriptor */
> > -       void (*tx_enable_tse)(struct sxgbe_tx_norm_desc *p, u8 is_tse,
> > -                               u32 hdr_len, u32 payload_len);
> > +       void (*tx_desc_enable_tse)(struct sxgbe_tx_norm_desc *p, u8
is_tse,
> > +                                  u32 total_hdr_len, u32 tcp_hdr_len,
> > +                                  u32 tcp_payload_len);
> >
> >         /* Assign buffer lengths for descriptor */
> >         void (*prepare_tx_desc)(struct sxgbe_tx_norm_desc *p, u8
> > is_fd, @@ -207,20 +208,26 @@ struct sxgbe_desc_ops {
> >         int (*get_tx_timestamp_status)(struct sxgbe_tx_norm_desc *p);
> >
> >         /* TX Context Descripto Specific */
> > -       void (*init_tx_ctxt_desc)(struct sxgbe_tx_ctxt_desc *p);
> > +       void (*tx_ctxt_desc_set_ctxt)(struct sxgbe_tx_ctxt_desc *p);
> >
> >         /* Set the owner of the TX context descriptor */
> > -       void (*set_tx_ctxt_owner)(struct sxgbe_tx_ctxt_desc *p);
> > +       void (*tx_ctxt_desc_set_owner)(struct sxgbe_tx_ctxt_desc *p);
> >
> >         /* Get the owner of the TX context descriptor */
> >         int (*get_tx_ctxt_owner)(struct sxgbe_tx_ctxt_desc *p);
> >
> >         /* Set TX mss */
> > -       void (*tx_ctxt_desc_setmss)(struct sxgbe_tx_ctxt_desc *p, int
mss);
> > +       void (*tx_ctxt_desc_set_mss)(struct sxgbe_tx_ctxt_desc *p, u16
> > + mss);
> >
> >         /* Set TX mss */
> >         int (*tx_ctxt_desc_get_mss)(struct sxgbe_tx_ctxt_desc *p);
> >
> > +       /* Set TX tcmssv */
> > +       void (*tx_ctxt_desc_set_tcmssv)(struct sxgbe_tx_ctxt_desc *p);
> > +
> > +       /* Reset TX ostc */
> > +       void (*tx_ctxt_desc_reset_ostc)(struct sxgbe_tx_ctxt_desc *p);
> > +
> >         /* Set IVLAN information */
> >         void (*tx_ctxt_desc_set_ivlantag)(struct sxgbe_tx_ctxt_desc *p,
> >                                           int is_ivlanvalid, int
> > ivlan_tag, diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.c
> > b/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.c
> > index 1e68ef3..1edc451 100644
> > --- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.c
> > +++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.c
> > @@ -354,6 +354,15 @@ static void sxgbe_dma_rx_watchdog(void __iomem
> *ioaddr, u32 riwt)
> >         }
> >  }
> >
> > +static void sxgbe_enable_tso(void __iomem *ioaddr, u8 chan_num) {
> > +       u32 ctrl;
> > +
> > +       ctrl = readl(ioaddr + SXGBE_DMA_CHA_TXCTL_REG(chan_num));
> > +       ctrl |= SXGBE_DMA_CHA_TXCTL_TSE_ENABLE;
> > +       writel(ctrl, ioaddr + SXGBE_DMA_CHA_TXCTL_REG(chan_num));
> > +}
> > +
> >  static const struct sxgbe_dma_ops sxgbe_dma_ops = {
> >         .init = sxgbe_dma_init,
> >         .cha_init = sxgbe_dma_channel_init, @@ -369,6 +378,7 @@ static
> > const struct sxgbe_dma_ops sxgbe_dma_ops = {
> >         .tx_dma_int_status = sxgbe_tx_dma_int_status,
> >         .rx_dma_int_status = sxgbe_rx_dma_int_status,
> >         .rx_watchdog = sxgbe_dma_rx_watchdog,
> > +       .enable_tso = sxgbe_enable_tso,
> >  };
> >
> >  const struct sxgbe_dma_ops *sxgbe_get_dma_ops(void) diff --git
> > a/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.h
> > b/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.h
> > index 50c8054..6c070ac 100644
> > --- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.h
> > +++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_dma.h
> > @@ -42,6 +42,8 @@ struct sxgbe_dma_ops {
> >                                  struct sxgbe_extra_stats *x);
> >         /* Program the HW RX Watchdog */
> >         void (*rx_watchdog)(void __iomem *ioaddr, u32 riwt);
> > +       /* Enable TSO for each DMA channel */
> > +       void (*enable_tso)(void __iomem *ioaddr, u8 chan_num);
> >  };
> >
> >  const struct sxgbe_dma_ops *sxgbe_get_dma_ops(void); diff --git
> > a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
> > b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
> > index 1714fd7..dc07ee6 100644
> > --- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
> > +++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
> > @@ -1099,6 +1099,28 @@ static int sxgbe_release(struct net_device *dev)
> >         return 0;
> >  }
> >
> > +/* Prepare first Tx descriptor for doing TSO operation */ void
> > +sxgbe_tso_prepare(struct sxgbe_priv_data *priv,
> > +                      struct sxgbe_tx_norm_desc *first_desc,
> > +                      struct sk_buff *skb) {
> > +       unsigned int total_hdr_len, tcp_hdr_len;
> > +
> > +       /* Write first Tx descriptor with appropriate value */
> > +       tcp_hdr_len = tcp_hdrlen(skb);
> > +       total_hdr_len = skb_transport_offset(skb) + tcp_hdr_len;
> > +
> > +       first_desc->tdes01 = dma_map_single(priv->device, skb->data,
> > +                                           total_hdr_len, DMA_TO_DEVICE);
> > +       if (dma_mapping_error(priv->device, first_desc->tdes01))
> > +               pr_err("%s: TX dma mapping failed!!\n", __func__);
> > +
> > +       first_desc->tdes23.tx_rd_des23.first_desc = 1;
> > +       priv->hw->desc->tx_desc_enable_tse(first_desc, 1, total_hdr_len,
> > +                                          tcp_hdr_len,
> > +                                          skb->len - total_hdr_len);
> > +}
> > +
> >  /**
> >   *  sxgbe_xmit: Tx entry point of the driver
> >   *  @skb : the socket buffer
> > @@ -1116,13 +1138,25 @@ static netdev_tx_t sxgbe_xmit(struct sk_buff
> *skb, struct net_device *dev)
> >         unsigned int tx_rsize = priv->dma_tx_size;
> >         struct sxgbe_tx_queue *tqueue = priv->txq[txq_index];
> >         struct sxgbe_tx_norm_desc *tx_desc, *first_desc;
> > +       struct sxgbe_tx_ctxt_desc *ctxt_desc = NULL;
> >         int nr_frags = skb_shinfo(skb)->nr_frags;
> >         int no_pagedlen = skb_headlen(skb);
> >         int is_jumbo = 0;
> > +       u16 mss;
> > +       u32 ctxt_desc_req = 0;
> >
> >         /* get the TX queue handle */
> >         dev_txq = netdev_get_tx_queue(dev, txq_index);
> >
> > +       if (unlikely(skb_is_gso(skb) &&
> > +                    tqueue->prev_mss != skb_shinfo(skb)->gso_size))
> > +               ctxt_desc_req = 1;
> > +
> > +       if (unlikely(vlan_tx_tag_present(skb) ||
> > +                    ((skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) &&
> > +                     tqueue->hwts_tx_en)))
> > +               ctxt_desc_req = 1;
> > +
> >         /* get the spinlock */
> >         spin_lock(&tqueue->tx_lock);
> >
> > @@ -1141,18 +1175,38 @@ static netdev_tx_t sxgbe_xmit(struct sk_buff
> *skb, struct net_device *dev)
> >         tx_desc = tqueue->dma_tx + entry;
> >
> >         first_desc = tx_desc;
> > +       if (ctxt_desc_req)
> > +               ctxt_desc = (struct sxgbe_tx_ctxt_desc *)first_desc;
> >
> >         /* save the skb address */
> >         tqueue->tx_skbuff[entry] = skb;
> >
> >         if (!is_jumbo) {
> > -               tx_desc->tdes01 = dma_map_single(priv->device, skb->data,
> > -                                                  no_pagedlen,
DMA_TO_DEVICE);
> > -               if (dma_mapping_error(priv->device, tx_desc->tdes01))
> > -                       pr_err("%s: TX dma mapping failed!!\n", __func__);
> > -
> > -               priv->hw->desc->prepare_tx_desc(tx_desc, 1, no_pagedlen,
> > -                                               no_pagedlen);
> > +               if (likely(skb_is_gso(skb))) {
> 
> We should also check for prev_mss and current mss also else we try to access
> null "ctxt_desc_mss" pointer because "ctxt_desc_mss" is initialized only if
> prev_mss != current mss.
OK.  It will be included in the next post.

> 
> > +                       /* TSO support */
> > +                       mss = skb_shinfo(skb)->gso_size;
> > +                       priv->hw->desc->tx_ctxt_desc_set_mss(ctxt_desc,
mss);
> > +
priv->hw->desc->tx_ctxt_desc_set_tcmssv(ctxt_desc);
> > +
priv->hw->desc->tx_ctxt_desc_reset_ostc(ctxt_desc);
> > +                       priv->hw->desc->tx_ctxt_desc_set_ctxt(ctxt_desc);
> > +
> > + priv->hw->desc->tx_ctxt_desc_set_owner(ctxt_desc);
> > +
> > +                       entry = (++tqueue->cur_tx) % tx_rsize;
> > +                       first_desc = tqueue->dma_tx + entry;
> > +
> > +                       sxgbe_tso_prepare(priv, first_desc, skb);
> > +
> > +                       tqueue->prev_mss = mss;
> > +               } else {
> > +                       tx_desc->tdes01 = dma_map_single(priv->device,
> > +                                                        skb->data,
no_pagedlen, DMA_TO_DEVICE);
> > +                       if (dma_mapping_error(priv->device,
tx_desc->tdes01))
> > +                               netdev_err(dev, "%s: TX dma mapping
failed!!\n",
> > +                                          __func__);
> > +
> > +                       priv->hw->desc->prepare_tx_desc(tx_desc, 1,
no_pagedlen,
> > +                                                       no_pagedlen);
> > +               }
> >         }
> >
> >         for (frag_num = 0; frag_num < nr_frags; frag_num++) { @@
> > -1859,6 +1913,7 @@ struct sxgbe_priv_data *sxgbe_dvr_probe(struct device
> *device,
> >         int ret = 0;
> >         struct net_device *ndev = NULL;
> >         struct sxgbe_priv_data *priv;
> > +       u8 queue_num;
> >
> >         ndev = alloc_etherdev_mqs(sizeof(struct sxgbe_priv_data),
> >                                   SXGBE_TX_QUEUES, SXGBE_RX_QUEUES);
> > @@ -1893,7 +1948,10 @@ struct sxgbe_priv_data *sxgbe_dvr_probe(struct
> > device *device,
> >
> >         ndev->netdev_ops = &sxgbe_netdev_ops;
> >
> > -       ndev->hw_features = NETIF_F_SG | NETIF_F_RXCSUM;
> > +       ndev->hw_features = NETIF_F_SG | NETIF_F_RXCSUM | NETIF_F_GRO;
> > +       if (priv->hw_cap.tcpseg_offload)
> > +               ndev->hw_features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
> > +                                    NETIF_F_TSO | NETIF_F_TSO6;
> >         ndev->features |= ndev->hw_features | NETIF_F_HIGHDMA;
> >         ndev->watchdog_timeo = msecs_to_jiffies(TX_TIMEO);
> >
> > @@ -1905,6 +1963,13 @@ struct sxgbe_priv_data *sxgbe_dvr_probe(struct
> device *device,
> >         if (flow_ctrl)
> >                 priv->flow_ctrl = SXGBE_FLOW_AUTO;      /* RX/TX pause on
*/
> >
> > +       /* Enable TCP segmentation offload for all DMA channels */
> > +       if (priv->hw_cap.tcpseg_offload) {
> > +               SXGBE_FOR_EACH_QUEUE(SXGBE_TX_QUEUES, queue_num) {
> > +                       priv->hw->dma->enable_tso(priv->ioaddr,
queue_num);
> > +               }
> > +       }
> > +
> >         /* Rx Watchdog is available, enable depend on platform data */
> >         if (!priv->plat->riwt_off) {
> >                 priv->use_riwt = 1;
> > --
> > 1.7.10.4
> >
> >
> > --
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