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Date: Fri, 14 Jun 2013 00:19:46 +0200
From: Francois Romieu <romieu@...zoreil.com>
To: Alexey Brodkin <Alexey.Brodkin@...opsys.com>
Cc: netdev@...r.kernel.org,
Andy Shevchenko <andy.shevchenko@...il.com>,
Joe Perches <joe@...ches.com>,
Vineet Gupta <Vineet.Gupta1@...opsys.com>,
Mischa Jonker <Mischa.Jonker@...opsys.com>,
Arnd Bergmann <arnd@...db.de>,
Grant Likely <grant.likely@...aro.org>,
Rob Herring <rob.herring@...xeda.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
"David S. Miller" <davem@...emloft.net>,
linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org
Subject: Re: [PATCH v3] ethernet/arc/arc_emac - Add new driver
Alexey Brodkin <Alexey.Brodkin@...opsys.com> :
[...]
> diff --git a/drivers/net/ethernet/arc/arc_emac.h b/drivers/net/ethernet/arc/arc_emac.h
> new file mode 100644
> index 0000000..6691db2
> --- /dev/null
> +++ b/drivers/net/ethernet/arc/arc_emac.h
[...]
> +struct arc_emac_priv {
> + struct net_device_stats stats;
> + unsigned int clock_frequency;
> + unsigned int max_speed;
> +
> + /* Pointers to BD rings - CPU side */
> + struct arc_emac_bd_t *rxbd;
There does not seem to be much need for rxbd->data.
> + struct arc_emac_bd_t *txbd;
[...]
> +static int arc_emac_get_settings(struct net_device *ndev,
> + struct ethtool_cmd *cmd)
> +{
> + struct arc_emac_priv *priv = netdev_priv(ndev);
> +
> + if (priv->phy_dev)
> + return phy_ethtool_gset(priv->phy_dev, cmd);
arc_emac_probe() succeeded : priv->phy_dev can't be NULL.
[...]
> +static int arc_emac_set_settings(struct net_device *ndev,
> + struct ethtool_cmd *cmd)
> +{
> + struct arc_emac_priv *priv = netdev_priv(ndev);
> +
> + if (!capable(CAP_NET_ADMIN))
> + return -EPERM;
> +
> + if (priv->phy_dev)
> + return phy_ethtool_sset(priv->phy_dev, cmd);
priv->phy_dev can't be NULL either.
[...]
> +static int arc_emac_poll(struct napi_struct *napi, int budget)
> +{
> + struct net_device *ndev = napi->dev;
> + struct arc_emac_priv *priv = netdev_priv(ndev);
> + unsigned int i, loop, work_done = 0;
> + struct sk_buff *skb;
> +
> + /* Loop thru the BD chain, but not always from 0.
> + * Start from right after where we last saw a packet.
> + */
> + i = priv->last_rx_bd;
> +
> + for (loop = 0; loop < RX_BD_NUM; loop++) {
> + struct net_device_stats *stats = &priv->stats;
> + struct buffer_state *rx_buff;
> + struct arc_emac_bd_t *rxbd;
> + dma_addr_t addr;
> + unsigned int info, pktlen;
> + unsigned int buflen = ndev->mtu + EMAC_BUFFER_PAD;
> +
> + i = (i + 1) % RX_BD_NUM;
> + rx_buff = &priv->rx_buff[i];
> + rxbd = &priv->rxbd[i];
> + info = rxbd->info;
You may / should update 'i' so that you can:
struct buffer_state *rx_buff = priv->rx_buff + i;
struct arc_emac_bd_t *rxbd = priv->rxbd + i;
unsigned int pktlen, info = rxbd->info;
> +
> + /* Process current BD */
> +
> + if (unlikely((info & OWN_MASK) == FOR_EMAC)) {
> + /* BD is still owned by EMAC */
> + continue;
> + }
Processing starts at priv->last_rx_bd. Could it not be a 'break' ?
[...]
> + pktlen = info & LEN_MASK;
> + stats->rx_packets++;
> + stats->rx_bytes += pktlen;
> + skb = rx_buff->skb;
> + skb_put(skb, pktlen);
> + skb->dev = ndev;
> + skb->protocol = eth_type_trans(skb, ndev);
> + netif_receive_skb(skb);
> +
> + dma_unmap_single(&ndev->dev,
> + dma_unmap_addr(&rx_buff, addr),
> + dma_unmap_len(&rx_buff, len),
> + DMA_FROM_DEVICE);
dma_unmap_single(&ndev->dev, dma_unmap_addr(&rx_buff, addr),
dma_unmap_len(&rx_buff, len), DMA_FROM_DEVICE);
Please unmap before netif_receive_skb.
> +
> + /* Prepare the BD for next cycle */
> + rx_buff->skb = netdev_alloc_skb_ip_align(ndev, buflen);
> + if (unlikely(!rx_buff->skb)) {
> + if (net_ratelimit())
> + netdev_err(ndev, "cannot allocate skb\n");
> + stats->rx_errors++;
> + continue;
> + }
The descriptor entry is left unchanged. Afaiu the driver will move to the
next descriptor and crash on dereferencing NULL (rx_buff->)skb next time
it wraps.
I suggest avoiding holes: don't netif_receive_skb if you can't alloc a new
skb.
[...]
> +static irqreturn_t arc_emac_intr(int irq, void *dev_instance)
> +{
> + struct net_device *ndev = dev_instance;
> + struct arc_emac_priv *priv = netdev_priv(ndev);
> + struct net_device_stats *stats = &priv->stats;
> + unsigned int status;
> +
> + status = arc_reg_get(priv, R_STATUS);
> + status &= ~MDIO_MASK;
> +
> + /* Reset all flags except "MDIO complete"*/
> + arc_reg_set(priv, R_STATUS, status);
> +
> + if (status & RXINT_MASK) {
> + if (likely(napi_schedule_prep(&priv->napi))) {
> + arc_reg_clr(priv, R_ENABLE, RXINT_MASK);
> + __napi_schedule(&priv->napi);
> + }
> + }
> +
> + if (status & TXINT_MASK) {
You may consider moving everything into the napi poll handler.
[...]
> +static int arc_emac_open(struct net_device *ndev)
> +{
> + struct arc_emac_priv *priv = netdev_priv(ndev);
> + struct phy_device *phy_dev = priv->phy_dev;
> + struct arc_emac_bd_t *bd;
> + struct sk_buff *skb;
> + int i;
> +
> + phy_dev->autoneg = AUTONEG_ENABLE;
> + phy_dev->speed = 0;
> + phy_dev->duplex = 0;
> + phy_dev->advertising = phy_dev->supported;
> +
> + if (priv->max_speed > 100) {
> + phy_dev->advertising &= PHY_GBIT_FEATURES;
> + } else if (priv->max_speed <= 100) {
> + phy_dev->advertising &= PHY_BASIC_FEATURES;
> + if (priv->max_speed <= 10) {
> + phy_dev->advertising &= ~SUPPORTED_100baseT_Half;
> + phy_dev->advertising &= ~SUPPORTED_100baseT_Full;
> + }
> + }
> +
> + /* Allocate and set buffers for Rx BD's */
> + bd = priv->rxbd;
> + for (i = 0; i < RX_BD_NUM; i++) {
> + skb = netdev_alloc_skb_ip_align(ndev, ndev->mtu +
> + EMAC_BUFFER_PAD);
> +
Missing NULL check.
[...]
> + /* Set BD ring pointers for device side */
> + arc_reg_set(priv, R_RX_RING,
> + (unsigned int)priv->rxbd_dma_hdl);
arc_reg_set(priv, R_RX_RING, (unsigned int)priv->rxbd_dma_hdl);
> +
> + arc_reg_set(priv, R_TX_RING,
> + (unsigned int)priv->rxbd_dma_hdl + RX_RING_SZ);
Forgot priv->txbd_dma_hdl ?
> +
> + /* Set Poll rate so that it polls every 1 ms */
> + arc_reg_set(priv, R_POLLRATE,
> + priv->clock_frequency / 1000000);
arc_reg_set(priv, R_POLLRATE, priv->clock_frequency / 1000000);
> +
> + /* Enable interrupts */
> + arc_reg_set(priv, R_ENABLE,
> + TXINT_MASK | RXINT_MASK | ERR_MASK);
arc_reg_set(priv, R_ENABLE, TXINT_MASK | RXINT_MASK | ERR_MASK);
> +
> + /* Set CONTROL */
> + arc_reg_set(priv, R_CTRL,
> + (RX_BD_NUM << 24) | /* RX BD table length */
> + (TX_BD_NUM << 16) | /* TX BD table length */
> + TXRN_MASK | RXRN_MASK);
> +
> + /* Enable EMAC */
> + arc_reg_or(priv, R_CTRL, EN_MASK);
> +
> + phy_start_aneg(priv->phy_dev);
> +
> + netif_start_queue(ndev);
> + napi_enable(&priv->napi);
napi must be enabled before the first rx packet / irq kicks in.
[...]
> +static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
> +{
> + struct arc_emac_priv *priv = netdev_priv(ndev);
> + unsigned int info, len, *txbd_curr = &priv->txbd_curr;
> + dma_addr_t addr;
> + char *pkt = skb->data;
> +
> + len = max_t(unsigned int, ETH_ZLEN, skb->len);
The device automatically pads, right ?
> + info = priv->txbd[*txbd_curr].info;
> +
> + /* EMAC still holds this buffer in its possession.
> + * CPU must not modify this buffer descriptor
> + */
> + if (unlikely((info & OWN_MASK) == FOR_EMAC)) {
> + netif_stop_queue(ndev);
> + return NETDEV_TX_BUSY;
It is more than unlikely: you may check for it as a bug but you should
stop_queue when the tx ring is full (before returning below).
> + }
> +
> + addr = dma_map_single(&ndev->dev, (void *)pkt, len, DMA_TO_DEVICE);
> + if (unlikely(dma_mapping_error(&ndev->dev, addr))) {
> + dev_kfree_skb(skb);
> + return NETDEV_TX_OK;
Please update tx_dropped stats.
> + }
> + dma_unmap_addr_set(&priv->tx_buff[*txbd_curr], mapping, addr);
> + dma_unmap_len_set(&priv->tx_buff[*txbd_curr], len, len);
> +
> + priv->tx_buff[*txbd_curr].skb = skb;
> + priv->txbd[*txbd_curr].data = pkt;
Insert memory barrier.
> + priv->txbd[*txbd_curr].info = FOR_EMAC | FRST_MASK | LAST_MASK | len;
> +
> + *txbd_curr = (*txbd_curr + 1) % TX_BD_NUM;
> +
> + arc_reg_set(priv, R_STATUS, TXPL_MASK);
> +
> + skb_tx_timestamp(skb);
> +
> + return NETDEV_TX_OK;
> +}
[...]
> +static int arc_emac_probe(struct platform_device *pdev)
> +{
[...]
> + err = arc_mdio_probe(pdev->dev.of_node, priv);
> + if (err) {
> + dev_err(&pdev->dev, "failed to probe MII bus\n");
> + goto out;
> + }
> +
> +
> + priv->phy_dev = of_phy_connect(ndev, priv->phy_node,
> + arc_emac_adjust_link, 0,
> + PHY_INTERFACE_MODE_MII);
> + if (!priv->phy_dev) {
> + netdev_err(ndev, "of_phy_connect() failed\n");
> + return -ENODEV;
arc_mdio_remove leak.
--
Ueimor
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