Re: [net-next,v20,4/7] net: mtip: Add net_device_ops functions to the L2 switch driver

[Jakub Kicinski <kuba@kernel.org>]

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net: mtip: Add net_device_ops functions to the L2 switch driver

This patch adds the net_device_ops callback implementations for the MTIP
L2 switch driver including transmit, timeout handling, multicast setup,
MAC address configuration, and port parent ID retrieval.

> diff --git a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c
> index 9c21a3d29c1c..a6424ee1a9d9 100644
> --- a/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c
> +++ b/drivers/net/ethernet/freescale/mtipsw/mtipl2sw.c

[ ... ]

> +static netdev_tx_t mtip_start_xmit_port(struct sk_buff *skb,
> +					struct net_device *dev, int port)
> +{

[ ... ]

> +	/* Push the data cache so the CPM does not get stale memory
> +	 * data.
> +	 */
> +	bdp->cbd_bufaddr = dma_map_single(&fep->pdev->dev, bufaddr,
> +					  MTIP_SWITCH_TX_FRSIZE,
> +					  DMA_TO_DEVICE);

The dma_map_single() call here creates a DMA mapping, but mtip_switch_tx()
at this point in the series is an empty stub that never calls
dma_unmap_single(). Is the intention for this to be resolved by a later
patch in the series? Looking ahead, a4c3fa1c66c9 ("net: mtip: Add
mtip_switch_{rx|tx} functions to the L2 switch driver") does add the full
TX completion handler with the dma_unmap_single() call. However, this
commit on its own could cause DMA resource exhaustion if used standalone
(e.g., during bisection).

Would it make sense to merge these two patches together, or at minimum
have a note in the commit message explaining the dependency?

[ ... ]