Subject: Re: [PATCH V3 net-next 2/2] net: broadcom: bcm4908_enet: add BCM4908 controller driver

From: Andrew Lunn <[email-masked]>
Date: Wed, 10 Feb 2021 03:39:15 +0100

> +static inline u32 enet_read(struct bcm4908_enet *enet, u16 offset)
> +{
> +	return readl(enet->base + offset);
> +}

No inline functions in C files please. Let the compiler decide.

> +static int bcm4908_dma_alloc_buf_descs(struct bcm4908_enet *enet,
> +				       struct bcm4908_enet_dma_ring *ring)
> +{
> +	int size = ring->length * sizeof(struct bcm4908_enet_dma_ring_bd);
> +	struct device *dev = enet->dev;
> +
> +	ring->cpu_addr = dma_alloc_coherent(dev, size, &ring->dma_addr, GFP_KERNEL);
> +	if (!ring->cpu_addr)
> +		return -ENOMEM;
> +
> +	if (((uintptr_t)ring->cpu_addr) & (0x40 - 1)) {
> +		dev_err(dev, "Invalid DMA ring alignment\n");
> +		goto err_free_buf_descs;
> +	}
> +
> +	ring->slots = kzalloc(ring->length * sizeof(*ring->slots), GFP_KERNEL);
> +	if (!ring->slots)
> +		goto err_free_buf_descs;
> +
> +	memset(ring->cpu_addr, 0, size);

It looks like dma_alloc_coherent() will perform a clear. See __dma_alloc_from_coherent()

> +static void bcm4908_enet_dma_reset(struct bcm4908_enet *enet)
> +{
> +	struct bcm4908_enet_dma_ring *rings[] = { &enet->rx_ring, &enet->tx_ring };
> +	int i;
> +
> +	/* Disable the DMA controller and channel */
> +	for (i = 0; i < ARRAY_SIZE(rings); i++)
> +		enet_write(enet, rings[i]->cfg_block + ENET_DMA_CH_CFG, 0);
> +	enet_maskset(enet, ENET_DMA_CONTROLLER_CFG, ENET_DMA_CTRL_CFG_MASTER_EN, 0);

Is there a need to wait for any in flight DMA transfers to complete
before you go further? Or is that what
bcm4908_enet_dma_rx_ring_disable() is doing?

> +
> +	/* Reset channels state */
> +	for (i = 0; i < ARRAY_SIZE(rings); i++) {
> +		struct bcm4908_enet_dma_ring *ring = rings[i];
> +
> +		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_BASE_DESC_PTR, 0);
> +		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_STATE_DATA, 0);
> +		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_DESC_LEN_STATUS, 0);
> +		enet_write(enet, ring->st_ram_block + ENET_DMA_CH_STATE_RAM_DESC_BASE_BUFPTR, 0);
> +	}
> +}
> +
> +static void bcm4908_enet_dma_tx_ring_ensable(struct bcm4908_enet *enet,
> +					     struct bcm4908_enet_dma_ring *ring)

enable not ensable?

> +static int bcm4908_enet_open(struct net_device *netdev)
> +{
> +	struct bcm4908_enet *enet = netdev_priv(netdev);
> +	struct device *dev = enet->dev;
> +	int err;
> +
> +	err = request_irq(netdev->irq, bcm4908_enet_irq_handler, 0, "enet", enet);
> +	if (err) {
> +		dev_err(dev, "Failed to request IRQ %d: %d\n", netdev->irq, err);
> +		return err;
> +	}
> +
> +	bcm4908_enet_gmac_init(enet);
> +	bcm4908_enet_dma_reset(enet);
> +	bcm4908_enet_dma_init(enet);
> +
> +	enet_umac_set(enet, UMAC_CMD, CMD_TX_EN | CMD_RX_EN);
> +
> +	enet_set(enet, ENET_DMA_CONTROLLER_CFG, ENET_DMA_CTRL_CFG_MASTER_EN);
> +	enet_maskset(enet, ENET_DMA_CONTROLLER_CFG, ENET_DMA_CTRL_CFG_FLOWC_CH1_EN, 0);
> +	bcm4908_enet_dma_rx_ring_enable(enet, &enet->rx_ring);
> +
> +	napi_enable(&enet->napi);
> +	netif_carrier_on(netdev);
> +	netif_start_queue(netdev);
> +
> +	bcm4908_enet_intrs_ack(enet);
> +	bcm4908_enet_intrs_on(enet);
> +
> +	return 0;
> +}

No PHY handling? It would be normal to connect the phy in open.

   Andrew