Subject: Re: [RFC v2 PATCH 02/10] net: ti: prueth: Adds ICSSM Ethernet driver

From: Simon Horman <[email-masked]>
Date: Thu, 30 Jan 2025 11:41:45 +0000

On Fri, Jan 24, 2025 at 05:53:45PM +0530, Basharath Hussain Khaja wrote:
> From: Roger Quadros <[email-masked]>
> 
> Updates Kernel configuration to enable PRUETH driver and its dependencies
> along with makefile changes to add the new PRUETH driver.
> 
> Changes includes init and deinit of ICSSM PRU Ethernet driver including
> net dev registration and firmware loading for DUAL-MAC mode running on
> PRU-ICSS2 instance.
> 
> Changes also includes link handling, PRU booting, default firmware loading
> and PRU stopping using existing remoteproc driver APIs.
> 
> Signed-off-by: Roger Quadros <[email-masked]>
> Signed-off-by: Andrew F. Davis <[email-masked]>
> Signed-off-by: Parvathi Pudi <[email-masked]>
> Signed-off-by: Basharath Hussain Khaja <[email-masked]>

...

> diff --git a/drivers/net/ethernet/ti/icssm/icssm_prueth.c b/drivers/net/ethernet/ti/icssm/icssm_prueth.c

...

> +static int icssm_emac_set_boot_pru(struct prueth_emac *emac,
> +				   struct net_device *ndev)
> +{
> +	const struct prueth_firmware *pru_firmwares;
> +	struct prueth *prueth = emac->prueth;
> +	const char *fw_name;
> +	int ret;
> +
> +	pru_firmwares = &prueth->fw_data->fw_pru[emac->port_id - 1];
> +	fw_name = pru_firmwares->fw_name[prueth->eth_type];
> +	if (!fw_name) {
> +		netdev_err(ndev, "eth_type %d not supported\n",
> +			   prueth->eth_type);
> +		return -ENODEV;
> +	}
> +
> +	ret = rproc_set_firmware(emac->pru, fw_name);
> +	if (ret) {
> +		netdev_err(ndev, "failed to set PRU0 firmware %s: %d\n",
> +			   fw_name, ret);
> +		return ret;
> +	}
> +
> +	ret = rproc_boot(emac->pru);
> +	if (ret) {
> +		netdev_err(ndev, "failed to boot PRU0: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +/**
> + * icssm_emac_ndo_open - EMAC device open
> + * @ndev: network adapter device
> + *
> + * Called when system wants to start the interface.
> + *
> + * Return: 0 for a successful open, or appropriate error code
> + */
> +static int icssm_emac_ndo_open(struct net_device *ndev)
> +{
> +	struct prueth_emac *emac = netdev_priv(ndev);
> +	int ret;
> +
> +	ret = icssm_emac_set_boot_pru(emac, ndev);
> +	if (ret)
> +		netdev_err(ndev, "failed to boot PRU: %d\n", ret);

Hi Roger, Basharath, all,

icssm_emac_set_boot_pru() already logs errors, including the one above.
So this log seems unnecessary to me.

Also, should an error be returned here?  If so, it looks like
icssm_emac_set_boot_pru() should release resources allocated by
rproc_set_firmware() if rproc_boot() fails.

> +
> +	/* start PHY */
> +	phy_start(emac->phydev);
> +
> +	return 0;
> +}

...

> +static int icssm_prueth_netdev_init(struct prueth *prueth,
> +				    struct device_node *eth_node)
> +{
> +	struct prueth_emac *emac;
> +	struct net_device *ndev;
> +	enum prueth_port port;
> +	enum prueth_mac mac;
> +	int ret;
> +
> +	port = icssm_prueth_node_port(eth_node);
> +	if (port == PRUETH_PORT_INVALID)
> +		return -EINVAL;
> +
> +	mac = icssm_prueth_node_mac(eth_node);
> +	if (mac == PRUETH_MAC_INVALID)
> +		return -EINVAL;
> +
> +	ndev = devm_alloc_etherdev(prueth->dev, sizeof(*emac));
> +	if (!ndev)
> +		return -ENOMEM;
> +
> +	SET_NETDEV_DEV(ndev, prueth->dev);
> +	emac = netdev_priv(ndev);
> +	prueth->emac[mac] = emac;
> +	emac->prueth = prueth;
> +	emac->ndev = ndev;
> +	emac->port_id = port;
> +
> +	/* by default eth_type is EMAC */
> +	switch (port) {
> +	case PRUETH_PORT_MII0:
> +		emac->pru = prueth->pru0;
> +		break;
> +	case PRUETH_PORT_MII1:
> +		emac->pru = prueth->pru1;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	/* get mac address from DT and set private and netdev addr */
> +	ret = of_get_ethdev_address(eth_node, ndev);
> +	if (!is_valid_ether_addr(ndev->dev_addr)) {
> +		eth_hw_addr_random(ndev);
> +		dev_warn(prueth->dev, "port %d: using random MAC addr: %pM\n",
> +			 port, ndev->dev_addr);
> +	}
> +	ether_addr_copy(emac->mac_addr, ndev->dev_addr);
> +
> +	/* connect PHY */
> +	emac->phydev = of_phy_get_and_connect(ndev, eth_node,
> +					      icssm_emac_adjust_link);
> +	if (!emac->phydev) {
> +		dev_dbg(prueth->dev, "PHY connection failed\n");
> +		ret = -EPROBE_DEFER;

Perhaps I misunderstand things, but if this occurs then
presumably icssm_prueth_netdev_init() will be called again.
And for each time this occirs another ndev will be allocated
by devm_alloc_etherdev(), each of which will only be freed
once the device is eventually torn-down.

I wonder if it would be better to free ndev here.
Which I think would imply using a non-mdev allocation for symmetry.

Similarly for resources allocated in the caller icssm_prueth_probe().

> +		goto free;
> +	}
> +
> +	/* remove unsupported modes */
> +	phy_remove_link_mode(emac->phydev, ETHTOOL_LINK_MODE_10baseT_Full_BIT);
> +
> +	phy_remove_link_mode(emac->phydev, ETHTOOL_LINK_MODE_10baseT_Half_BIT);
> +	phy_remove_link_mode(emac->phydev, ETHTOOL_LINK_MODE_100baseT_Half_BIT);
> +
> +	phy_remove_link_mode(emac->phydev, ETHTOOL_LINK_MODE_Pause_BIT);
> +	phy_remove_link_mode(emac->phydev, ETHTOOL_LINK_MODE_Asym_Pause_BIT);
> +
> +	ndev->netdev_ops = &emac_netdev_ops;
> +
> +	return 0;
> +free:

nit: This doesn't free anything.

> +	prueth->emac[mac] = NULL;
> +
> +	return ret;
> +}

...