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Date: Mon, 17 Mar 2014 14:25:50 -0700
From: Joe Perches <joe@...ches.com>
To: Byungho An <bh74.an@...sung.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
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;
I don't understand why the first test is < and the
subsequent tests are <= though.
> +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()
[]
> +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);
[]
> +/* 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);
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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