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Date: Mon, 17 Mar 2014 16:07:32 -0700
From: Byungho An <bh74.an@...sung.com>
To: 'Joe Perches' <joe@...ches.com>
Cc: netdev@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
davem@...emloft.net, siva.kallam@...sung.com,
vipul.pandya@...sung.com, ks.giri@...sung.com,
ilho215.lee@...sung.com
Subject: RE: [PATCH V3 2/8] net: sxgbe: add basic framework for Samsung 10Gb
ethernet driver
Joe Perches <joe@...ches.com> :
> On Mon, 2014-03-17 at 13:43 -0700, Byungho An wrote:
> > From: Siva Reddy <siva.kallam@...sung.com>
> >
> > This patch adds support for Samsung 10Gb ethernet driver(sxgbe).
>
> Sorry about the brevity, but this driver is very long and I don't like to
read that
> much at a time, so this is very superficial and I didn't read the whole
thing.
>
> Trivial notes:
>
> > diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
> > b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
>
> []
>
> > +static void sxgbe_clk_csr_set(struct sxgbe_priv_data *priv) {
> > + u32 clk_rate = clk_get_rate(priv->sxgbe_clk);
> > +
> > + /* assign the proper divider, this will be used during
> > + * mdio communication
> > + */
> > + if (clk_rate < SXGBE_CSR_F_150M)
> > + priv->clk_csr = SXGBE_CSR_100_150M;
> > + else if ((clk_rate >= SXGBE_CSR_F_150M) &&
> > + (clk_rate <= SXGBE_CSR_F_250M))
> > + priv->clk_csr = SXGBE_CSR_150_250M;
> > + else if ((clk_rate >= SXGBE_CSR_F_250M) &&
> > + (clk_rate <= SXGBE_CSR_F_300M))
> > + priv->clk_csr = SXGBE_CSR_250_300M;
> > + else if ((clk_rate >= SXGBE_CSR_F_300M) &&
> > + (clk_rate <= SXGBE_CSR_F_350M))
> > + priv->clk_csr = SXGBE_CSR_300_350M;
> > + else if ((clk_rate >= SXGBE_CSR_F_350M) &&
> > + (clk_rate <= SXGBE_CSR_F_400M))
> > + priv->clk_csr = SXGBE_CSR_350_400M;
> > + else if ((clk_rate >= SXGBE_CSR_F_400M) &&
> > + (clk_rate <= SXGBE_CSR_F_500M))
> > + priv->clk_csr = SXGBE_CSR_400_500M; }
>
> This block is unnecessarily hard to read and would be better without the
> superfluous tests as:
>
> if (clk_rate < SXGBE_CSR_F_150M)
> priv->clk_csr = SXGBE_CSR_100_150M;
> else if (clk_rate <= SXGBE_CSR_F_250M)
> priv->clk_csr = SXGBE_CSR_150_250M;
> else if (clk_rate <= SXGBE_CSR_F_300M)
> priv->clk_csr = SXGBE_CSR_250_300M;
> else if (clk_rate <= SXGBE_CSR_F_350M)
> priv->clk_csr = SXGBE_CSR_300_350M;
> else if (clk_rate <= SXGBE_CSR_F_400M)
> priv->clk_csr = SXGBE_CSR_350_400M;
> else if (clk_rate <= SXGBE_CSR_F_500M)
> priv->clk_csr = SXGBE_CSR_400_500M;
>
OK.
> I don't understand why the first test is < and the subsequent tests are <=
> though.
Because priv->clk should be set SXGBE_CSR_150_250M when clk_rate is 150M.
>
> > +static int init_tx_ring(struct device *dev, u8 queue_no,
> > + struct sxgbe_tx_queue *tx_ring, int tx_rsize)
> > +{
> []
> > + /* allocate memory for TX descriptors */
> > + tx_ring->dma_tx = dma_zalloc_coherent(dev,
> > + tx_rsize * sizeof(struct
> sxgbe_tx_norm_desc),
> > + &tx_ring->dma_tx_phy,
> GFP_KERNEL);
> > + if (!tx_ring->dma_tx) {
> > + dev_err(dev, "No memory for TX desc of SXGBE\n");
> > + return -ENOMEM;
> > + }
> > +
> > + /* allocate memory for TX skbuff array */
> > + tx_ring->tx_skbuff_dma = devm_kcalloc(dev, tx_rsize,
> > + sizeof(dma_addr_t), GFP_KERNEL);
> > + if (!tx_ring->tx_skbuff_dma) {
> > + dev_err(dev, "No memory for TX skbuffs DMA of SXGBE\n");
> > + goto dmamem_err;
> > + }
> > +
> > + tx_ring->tx_skbuff = devm_kcalloc(dev, tx_rsize,
> > + sizeof(struct sk_buff *),
GFP_KERNEL);
> > +
> > + if (!tx_ring->tx_skbuff) {
> > + dev_err(dev, "No memory for TX skbuffs of SXGBE\n");
> > + goto dmamem_err;
> > + }
>
> All the OOM messages like these are unnecessary as there is an existing
> generic OOM on allocation failures and a dump_stack()
OK. These will be removed.
>
> []
>
> > +static netdev_tx_t sxgbe_xmit(struct sk_buff *skb, struct net_device
> > +*dev) {
> []
> > + /* display current ring */
> > + if (netif_msg_pktdata(priv)) {
> > + netdev_dbg(dev, "%s: curr %d dirty=%d entry=%d, first=%p,
> nfrags=%d\n",
> > + __func__, (tqueue->cur_tx % tx_rsize),
> > + (tqueue->dirty_tx % tx_rsize), entry,
> > + first_desc, nr_frags);
>
> These 2 lines can be combined (and unnecessary parentheses removed)
> into:
>
> netif_dbg(priv, pktdata, dev, "%s: curr %d dirty=%d entry=%d,
first=%p,
> nfrags=%d\n",
> __func__, tqueue->cur_tx % tx_rsize,
> tqueue->dirty_tx % tx_rsize, entry,
> first_desc, nr_frags);
>
OK. Thanks.
> []
>
> > +/* sxgbe_get_stats64 - entry point to see statistical information of
> > +device
> > + * @dev : device pointer.
> > + * @stats : pointer to hold all the statistical information of device.
> > + * Description:
> > + * This function is a driver entry point whenever ifconfig command
> > +gets
> > + * executed to see device statistics. Statistics are number of
> > + * bytes sent or received, errors occured etc.
> > + * Return value:
> > + * This function returns various statistical information of device.
> > + */
> > +static struct rtnl_link_stats64 *sxgbe_get_stats64(struct net_device
*dev,
> > + struct rtnl_link_stats64
*stats)
> {
> > + struct sxgbe_priv_data *priv = netdev_priv(dev);
> > + void __iomem *ioaddr = priv->ioaddr;
> > + u64 count;
> > +
> > + spin_lock(&priv->stats_lock);
> > + /* Freeze the counter registers before reading value otherwise it may
> > + * get updated by hardware while we are reading them
> > + */
> > + writel(SXGBE_MMC_CTRL_CNT_FRZ, ioaddr + SXGBE_MMC_CTL_REG);
> > +
> > + stats->rx_bytes = readl(ioaddr +
> SXGBE_MMC_RXOCTETLO_GCNT_REG);
> > + stats->rx_bytes |= (u64)(readl(ioaddr +
> SXGBE_MMC_RXOCTETHI_GCNT_REG))
> > + << 32;
>
> Perhaps it'd be better to use a macro or a function to return a u64 like:
>
> static inline u64 sxgbe_get_stat64(void __iomem *ioaddr, int reg_lo, int
reg_hi)
> {
> u64 val = readl(ioaddr + reg_lo);
> val |= ((u64)readl(ioaddr + reg_hi)) << 32;
> return val;
> }
>
> > + stats->rx_packets = readl(ioaddr +
> SXGBE_MMC_RXFRAMELO_GBCNT_REG);
> > + stats->rx_packets |=
> > + (u64)(readl(ioaddr + SXGBE_MMC_RXFRAMEHI_GBCNT_REG))
> << 32;
>
> So this would be:
>
> stats->rx_packets = sxgbe_get_stat64(ioaddr,
> SXGBE_MMC_RXFRAMELO_GBCNT_REG,
> SXGBE_MMC_RXFRAMEHI_GBCNT_REG);
Good suggestion.
>
> It's a pity all of these registers don't have the same form as there could
then be
> a macro to simplify that long line and maybe remove the
> SXGBE_MMC_<foo>_REG uses.
>
> > + stats->multicast = readl(ioaddr +
> SXGBE_MMC_RXMULTILO_GCNT_REG);
> > + stats->multicast |= (u64)(readl(ioaddr +
> SXGBE_MMC_RXMULTIHI_GCNT_REG))
> > + << 32;
> > + stats->rx_crc_errors = readl(ioaddr + SXGBE_MMC_RXCRCERRLO_REG);
> > + stats->rx_crc_errors |= (u64)(readl(ioaddr +
> SXGBE_MMC_RXCRCERRHI_REG))
> > + << 32;
> > + stats->rx_length_errors = readl(ioaddr +
> SXGBE_MMC_RXLENERRLO_REG);
> > + stats->rx_length_errors |=
> > + (u64)(readl(ioaddr + SXGBE_MMC_RXLENERRHI_REG)) << 32;
>
>
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