Re: [net-next v14 07/12] net: mtip: Add mtip_switch_{rx|tx} functions to the L2 switch driver

[Lukasz Majewski <lukma@denx.de>]

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Hi Paolo,

> On 7/1/25 1:49 PM, Lukasz Majewski wrote:
> > diff --git a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c
> > b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c index
> > 63afdf2beea6..b5a82748b39b 100644 ---
> > a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c +++
> > b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c @@ -228,6
> > +228,39 @@ struct mtip_port_info *mtip_portinfofifo_read(struct
> > switch_enet_private *fep) return info; }
> >  
> > +static void mtip_atable_get_entry_port_number(struct
> > switch_enet_private *fep,
> > +					      unsigned char
> > *mac_addr, u8 *port) +{
> > +	int block_index, block_index_end, entry;
> > +	u32 mac_addr_lo, mac_addr_hi;
> > +	u32 read_lo, read_hi;
> > +
> > +	mac_addr_lo = (u32)((mac_addr[3] << 24) | (mac_addr[2] <<
> > 16) |
> > +			    (mac_addr[1] << 8) | mac_addr[0]);
> > +	mac_addr_hi = (u32)((mac_addr[5] << 8) | (mac_addr[4]));
> > +
> > +	block_index = GET_BLOCK_PTR(crc8_calc(mac_addr));
> > +	block_index_end = block_index + ATABLE_ENTRY_PER_SLOT;
> > +
> > +	/* now search all the entries in the selected block */
> > +	for (entry = block_index; entry < block_index_end;
> > entry++) {
> > +		mtip_read_atable(fep, entry, &read_lo, &read_hi);
> > +		*port = MTIP_PORT_FORWARDING_INIT;
> > +
> > +		if (read_lo == mac_addr_lo &&
> > +		    ((read_hi & 0x0000FFFF) ==
> > +		     (mac_addr_hi & 0x0000FFFF))) {
> > +			/* found the correct address */
> > +			if ((read_hi & (1 << 16)) && (!(read_hi &
> > (1 << 17))))
> > +				*port = FIELD_GET(AT_PORT_MASK,
> > read_hi);
> > +			break;
> > +		}
> > +	}
> > +
> > +	dev_dbg(&fep->pdev->dev, "%s: MAC: %pM PORT: 0x%x\n",
> > __func__,
> > +		mac_addr, *port);
> > +}
> > +
> >  /* Clear complete MAC Look Up Table */
> >  void mtip_clear_atable(struct switch_enet_private *fep)
> >  {
> > @@ -825,11 +858,217 @@ static irqreturn_t mtip_interrupt(int irq,
> > void *ptr_fep) 
> >  static void mtip_switch_tx(struct net_device *dev)
> >  {
> > +	struct mtip_ndev_priv *priv = netdev_priv(dev);
> > +	struct switch_enet_private *fep = priv->fep;
> > +	unsigned short status;
> > +	struct sk_buff *skb;
> > +	struct cbd_t *bdp;
> > +
> > +	spin_lock(&fep->hw_lock);
> > +	bdp = fep->dirty_tx;
> > +
> > +	while (((status = bdp->cbd_sc) & BD_ENET_TX_READY) == 0) {
> > +		if (bdp == fep->cur_tx && fep->tx_full == 0)
> > +			break;
> > +
> > +		dma_unmap_single(&fep->pdev->dev, bdp->cbd_bufaddr,
> > +				 MTIP_SWITCH_TX_FRSIZE,
> > DMA_TO_DEVICE);
> > +		bdp->cbd_bufaddr = 0;
> > +		skb = fep->tx_skbuff[fep->skb_dirty];
> > +		/* Check for errors */
> > +		if (status & (BD_ENET_TX_HB | BD_ENET_TX_LC |
> > +				   BD_ENET_TX_RL | BD_ENET_TX_UN |
> > +				   BD_ENET_TX_CSL)) {
> > +			dev->stats.tx_errors++;
> > +			if (status & BD_ENET_TX_HB)  /* No
> > heartbeat */
> > +				dev->stats.tx_heartbeat_errors++;
> > +			if (status & BD_ENET_TX_LC)  /* Late
> > collision */
> > +				dev->stats.tx_window_errors++;
> > +			if (status & BD_ENET_TX_RL)  /* Retrans
> > limit */
> > +				dev->stats.tx_aborted_errors++;
> > +			if (status & BD_ENET_TX_UN)  /* Underrun */
> > +				dev->stats.tx_fifo_errors++;
> > +			if (status & BD_ENET_TX_CSL) /* Carrier
> > lost */
> > +				dev->stats.tx_carrier_errors++;
> > +		} else {
> > +			dev->stats.tx_packets++;
> > +		}
> > +
> > +		if (status & BD_ENET_TX_READY)
> > +			dev_err(&fep->pdev->dev,
> > +				"Enet xmit interrupt and
> > TX_READY.\n"); +
> > +		/* Deferred means some collisions occurred during
> > transmit,
> > +		 * but we eventually sent the packet OK.
> > +		 */
> > +		if (status & BD_ENET_TX_DEF)
> > +			dev->stats.collisions++;
> > +
> > +		/* Free the sk buffer associated with this last
> > transmit */
> > +		dev_consume_skb_irq(skb);
> > +		fep->tx_skbuff[fep->skb_dirty] = NULL;
> > +		fep->skb_dirty = (fep->skb_dirty + 1) &
> > TX_RING_MOD_MASK; +
> > +		/* Update pointer to next buffer descriptor to be
> > transmitted */
> > +		if (status & BD_ENET_TX_WRAP)
> > +			bdp = fep->tx_bd_base;
> > +		else
> > +			bdp++;
> > +
> > +		/* Since we have freed up a buffer, the ring is no
> > longer
> > +		 * full.
> > +		 */
> > +		if (fep->tx_full) {
> > +			fep->tx_full = 0;
> > +			if (netif_queue_stopped(dev))
> > +				netif_wake_queue(dev);
> > +		}
> > +	}
> > +	fep->dirty_tx = bdp;
> > +	spin_unlock(&fep->hw_lock);
> >  }
> >  
> > +/* During a receive, the cur_rx points to the current incoming
> > buffer.
> > + * When we update through the ring, if the next incoming buffer has
> > + * not been given to the system, we just set the empty indicator,
> > + * effectively tossing the packet.
> > + */
> >  static int mtip_switch_rx(struct net_device *dev, int budget, int
> > *port) {
> > -	return -ENOMEM;
> > +	struct mtip_ndev_priv *priv = netdev_priv(dev);
> > +	u8 *data, rx_port = MTIP_PORT_FORWARDING_INIT;
> > +	struct switch_enet_private *fep = priv->fep;
> > +	unsigned short status, pkt_len;
> > +	struct net_device *pndev;
> > +	struct ethhdr *eth_hdr;
> > +	int pkt_received = 0;
> > +	struct sk_buff *skb;
> > +	struct cbd_t *bdp;
> > +	struct page *page;
> > +
> > +	/* First, grab all of the stats for the incoming packet.
> > +	 * These get messed up if we get called due to a busy
> > condition.
> > +	 */
> > +	bdp = fep->cur_rx;
> > +
> > +	while (!((status = bdp->cbd_sc) & BD_ENET_RX_EMPTY)) {
> > +		if (pkt_received >= budget)
> > +			break;
> > +
> > +		pkt_received++;
> > +
> > +		if (!fep->usage_count)
> > +			goto rx_processing_done;
> > +
> > +		status ^= BD_ENET_RX_LAST;
> > +		/* Check for errors. */
> > +		if (status & (BD_ENET_RX_LG | BD_ENET_RX_SH |
> > BD_ENET_RX_NO |
> > +			      BD_ENET_RX_CR | BD_ENET_RX_OV |
> > BD_ENET_RX_LAST |
> > +			      BD_ENET_RX_CL)) {
> > +			dev->stats.rx_errors++;
> > +			if (status & BD_ENET_RX_OV) {
> > +				/* FIFO overrun */
> > +				dev->stats.rx_fifo_errors++;
> > +				goto rx_processing_done;
> > +			}
> > +			if (status & (BD_ENET_RX_LG | BD_ENET_RX_SH
> > +				      | BD_ENET_RX_LAST)) {
> > +				/* Frame too long or too short. */
> > +				dev->stats.rx_length_errors++;
> > +				if (status & BD_ENET_RX_LAST)
> > +					netdev_err(dev, "rcv is
> > not +last\n");
> > +			}
> > +			if (status & BD_ENET_RX_CR)	/* CRC
> > Error */
> > +				dev->stats.rx_crc_errors++;
> > +
> > +			/* Report late collisions as a frame
> > error. */
> > +			if (status & (BD_ENET_RX_NO |
> > BD_ENET_RX_CL))
> > +				dev->stats.rx_frame_errors++;
> > +			goto rx_processing_done;
> > +		}
> > +
> > +		/* Get correct RX page */
> > +		page = fep->page[bdp - fep->rx_bd_base];
> > +		/* Process the incoming frame */
> > +		pkt_len = bdp->cbd_datlen;
> > +		data = (__u8 *)__va(bdp->cbd_bufaddr);
> > +
> > +		dma_sync_single_for_cpu(&fep->pdev->dev,
> > bdp->cbd_bufaddr,
> > +					pkt_len, DMA_FROM_DEVICE);
> > +		net_prefetch(page_address(page));  
> 
> Both `__va(bdp->cbd_bufaddr)` and `page_address(page)` should point to
> the same same memory. Please use constantly one _or_ the other  -
> likely page_address(page) is the best option.

Yes, the __va() can be replaced with page_address(page) as those are
the same addresses.

> 
> > +
> > +		if (fep->quirks & FEC_QUIRK_SWAP_FRAME)
> > +			swap_buffer(data, pkt_len);
> > +
> > +		if (data) {  
> 
> The above check is not needed. If data is null swap_buffer will still
> unconditionally dereference it.

+1

> 
> Also it looks like it can't be NULL.

Yes, those buffers are allocated at the initialization phase - if the
allocation fails, driver is not operational.

> 
> /P
> 




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH, Managing Director: Johanna Denk,
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Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

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