linux-kernel - Re: [PATCH net-next v2 8/9] microchip: lan865x: add driver support for Microchip's LAN865X MACPHY

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Date:   Tue, 24 Oct 2023 04:33:44 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Parthiban Veerasooran <Parthiban.Veerasooran@...rochip.com>
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        corbet@....net, steen.hegelund@...rochip.com,
        rdunlap@...radead.org, horms@...nel.org, casper.casan@...il.com,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        horatiu.vultur@...rochip.com, Woojung.Huh@...rochip.com,
        Nicolas.Ferre@...rochip.com, UNGLinuxDriver@...rochip.com,
        Thorsten.Kummermehr@...rochip.com
Subject: Re: [PATCH net-next v2 8/9] microchip: lan865x: add driver support
 for Microchip's LAN865X MACPHY

> +static int lan865x_set_hw_macaddr(struct net_device *netdev)
> +{
> +	u32 regval;
> +	bool ret;
> +	struct lan865x_priv *priv = netdev_priv(netdev);
> +	const u8 *mac = netdev->dev_addr;
> +
> +	ret = oa_tc6_read_register(priv->tc6, LAN865X_MAC_NCR, &regval);
> +	if (ret)
> +		goto error_mac;
> +	if ((regval & LAN865X_TXEN) | (regval & LAN865X_RXEN)) {

Would testing netif_running(netdev) be enough? That is a more common
test you see. In fact, you already have that in
lan865x_set_mac_address(). And in lan865x_probe() why would the
hardware be enabled?


> +		if (netif_msg_drv(priv))
> +			netdev_warn(netdev, "Hardware must be disabled for MAC setting\n");
> +		return -EBUSY;
> +	}
> +	/* MAC address setting */
> +	regval = (mac[3] << 24) | (mac[2] << 16) | (mac[1] << 8) | mac[0];
> +	ret = oa_tc6_write_register(priv->tc6, LAN865X_MAC_SAB1, regval);
> +	if (ret)
> +		goto error_mac;
> +
> +	regval = (mac[5] << 8) | mac[4];
> +	ret = oa_tc6_write_register(priv->tc6, LAN865X_MAC_SAT1, regval);
> +	if (ret)
> +		goto error_mac;
> +
> +	return 0;
> +
> +error_mac:
> +	return -ENODEV;

oa_tc6_write_register() should return an error code, so return it.

> +static int lan865x_set_mac_address(struct net_device *netdev, void *addr)
> +{
> +	struct sockaddr *address = addr;
> +
> +	if (netif_running(netdev))
> +		return -EBUSY;
> +
> +	eth_hw_addr_set(netdev, address->sa_data);
> +
> +	return lan865x_set_hw_macaddr(netdev);

You should ideally only update the netdev MAC address, if you managed
to change the value in the hardware.

> +static void lan865x_set_multicast_list(struct net_device *netdev)
> +{
> +	struct lan865x_priv *priv = netdev_priv(netdev);
> +	u32 regval = 0;
> +
> +	if (netdev->flags & IFF_PROMISC) {
> +		/* Enabling promiscuous mode */
> +		regval |= MAC_PROMISCUOUS_MODE;
> +		regval &= (~MAC_MULTICAST_MODE);
> +		regval &= (~MAC_UNICAST_MODE);
> +	} else if (netdev->flags & IFF_ALLMULTI) {
> +		/* Enabling all multicast mode */
> +		regval &= (~MAC_PROMISCUOUS_MODE);
> +		regval |= MAC_MULTICAST_MODE;
> +		regval &= (~MAC_UNICAST_MODE);
> +	} else if (!netdev_mc_empty(netdev)) {
> +		/* Enabling specific multicast addresses */
> +		struct netdev_hw_addr *ha;
> +		u32 hash_lo = 0;
> +		u32 hash_hi = 0;
> +
> +		netdev_for_each_mc_addr(ha, netdev) {
> +			u32 bit_num = lan865x_hash(ha->addr);
> +			u32 mask = 1 << (bit_num & 0x1f);
> +
> +			if (bit_num & 0x20)
> +				hash_hi |= mask;
> +			else
> +				hash_lo |= mask;
> +		}
> +		if (oa_tc6_write_register(priv->tc6, LAN865X_MAC_HRT, hash_hi)) {
> +			if (netif_msg_timer(priv))
> +				netdev_err(netdev, "Failed to write reg_hashh");
> +			return;
> +		}
> +		if (oa_tc6_write_register(priv->tc6, LAN865X_MAC_HRB, hash_lo)) {
> +			if (netif_msg_timer(priv))
> +				netdev_err(netdev, "Failed to write reg_hashl");
> +			return;
> +		}
> +		regval &= (~MAC_PROMISCUOUS_MODE);
> +		regval &= (~MAC_MULTICAST_MODE);
> +		regval |= MAC_UNICAST_MODE;
> +	} else {
> +		/* enabling local mac address only */
> +		if (oa_tc6_write_register(priv->tc6, LAN865X_MAC_HRT, regval)) {
> +			if (netif_msg_timer(priv))
> +				netdev_err(netdev, "Failed to write reg_hashh");
> +			return;
> +		}
> +		if (oa_tc6_write_register(priv->tc6, LAN865X_MAC_HRB, regval)) {
> +			if (netif_msg_timer(priv))
> +				netdev_err(netdev, "Failed to write reg_hashl");
> +			return;
> +		}
> +	}
> +	if (oa_tc6_write_register(priv->tc6, LAN865X_MAC_NCFGR, regval)) {
> +		if (netif_msg_timer(priv))
> +			netdev_err(netdev, "Failed to enable promiscuous mode");
> +	}
> +}

Another of those big functions which could be lots of simple functions
each doing one thing.

> +/* Configures the number of bytes allocated to each buffer in the
> + * transmit/receive queue. LAN865x supports only 64 and 32 bytes cps and also 64
> + * is the default value. So it is enough to configure the queue buffer size only
> + * for 32 bytes. Generally cps can't be changed during run time and also it is
> + * configured in the device tree. The values for the Tx/Rx queue buffer size are
> + * taken from the LAN865x datasheet.
> + */

Its unclear why this needs to be a callback. Why not just set it after
oa_tc6_init() returns?

> +static void lan865x_remove(struct spi_device *spi)
> +{
> +	struct lan865x_priv *priv = spi_get_drvdata(spi);
> +
> +	oa_tc6_exit(priv->tc6);
> +	unregister_netdev(priv->netdev);

Is that the correct order? Seems like you should unregister the netdev
first.

> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id lan865x_acpi_ids[] = {
> +	{ .id = "LAN865X",
> +	},
> +	{},

Does this work? You don't have access to the device tree properties.

     Andrew