Subject: Re: [PATCH net-next v3 2/4] net: ethernet: altera-tse: Convert to mdio-regmap and use PCS Lynx

From: Simon Horman <[email-masked]>
Date: Fri, 26 May 2023 10:39:08 +0200

On Fri, May 26, 2023 at 09:42:50AM +0200, Maxime Chevallier wrote:
> The newly introduced regmap-based MDIO driver allows for an easy mapping
> of an mdiodevice onto the memory-mapped TSE PCS, which is actually a
> Lynx PCS.
> 
> Convert Altera TSE to use this PCS instead of the pcs-altera-tse, which
> is nothing more than a memory-mapped Lynx PCS.
> 
> Signed-off-by: Maxime Chevallier <[email-masked]>

Hi Maxime,

I have some concerns about the error paths in this patch.

...

> @@ -1134,13 +1136,21 @@ static int altera_tse_probe(struct platform_device *pdev)
>  	const struct of_device_id *of_id = NULL;
>  	struct altera_tse_private *priv;
>  	struct resource *control_port;
> +	struct regmap *pcs_regmap;
>  	struct resource *dma_res;
>  	struct resource *pcs_res;
> +	struct mii_bus *pcs_bus;
>  	struct net_device *ndev;
>  	void __iomem *descmap;
> -	int pcs_reg_width = 2;
>  	int ret = -ENODEV;
>  
> +	struct regmap_config pcs_regmap_cfg;

nit: this probably belongs in with the bunch of declarations above it.

> +
> +	struct mdio_regmap_config mrc = {
> +		.parent = &pdev->dev,
> +		.valid_addr = 0x0,
> +	};

nit: maybe this too.

> +
>  	ndev = alloc_etherdev(sizeof(struct altera_tse_private));
>  	if (!ndev) {
>  		dev_err(&pdev->dev, "Could not allocate network device\n");
> @@ -1258,10 +1268,29 @@ static int altera_tse_probe(struct platform_device *pdev)
>  	ret = request_and_map(pdev, "pcs", &pcs_res,
>  			      &priv->pcs_base);
>  	if (ret) {
> +		/* If we can't find a dedicated resource for the PCS, fallback
> +		 * to the internal PCS, that has a different address stride
> +		 */
>  		priv->pcs_base = priv->mac_dev + tse_csroffs(mdio_phy0);
> -		pcs_reg_width = 4;
> +		pcs_regmap_cfg.reg_bits = 32;
> +		/* Values are MDIO-like values, on 16 bits */
> +		pcs_regmap_cfg.val_bits = 16;
> +		pcs_regmap_cfg.reg_shift = REGMAP_UPSHIFT(2);
> +	} else {
> +		pcs_regmap_cfg.reg_bits = 16;
> +		pcs_regmap_cfg.val_bits = 16;
> +		pcs_regmap_cfg.reg_shift = REGMAP_UPSHIFT(1);
>  	}
>  
> +	/* Create a regmap for the PCS so that it can be used by the PCS driver */
> +	pcs_regmap = devm_regmap_init_mmio(&pdev->dev, priv->pcs_base,
> +					   &pcs_regmap_cfg);
> +	if (IS_ERR(pcs_regmap)) {
> +		ret = PTR_ERR(pcs_regmap);
> +		goto err_free_netdev;
> +	}
> +	mrc.regmap = pcs_regmap;
> +
>  	/* Rx IRQ */
>  	priv->rx_irq = platform_get_irq_byname(pdev, "rx_irq");
>  	if (priv->rx_irq == -ENXIO) {
> @@ -1384,7 +1413,20 @@ static int altera_tse_probe(struct platform_device *pdev)
>  			 (unsigned long) control_port->start, priv->rx_irq,
>  			 priv->tx_irq);
>  
> -	priv->pcs = alt_tse_pcs_create(ndev, priv->pcs_base, pcs_reg_width);
> +	snprintf(mrc.name, MII_BUS_ID_SIZE, "%s-pcs-mii", ndev->name);
> +	pcs_bus = devm_mdio_regmap_register(&pdev->dev, &mrc);
> +	if (IS_ERR(pcs_bus)) {
> +		ret = PTR_ERR(pcs_bus);
> +		goto err_init_phy;
> +	}
> +
> +	priv->pcs_mdiodev = mdio_device_create(pcs_bus, 0);

mdio_device_create() can fail. Should that be handled here?

> +
> +	priv->pcs = lynx_pcs_create(priv->pcs_mdiodev);
> +	if (!priv->pcs) {
> +		ret = -ENODEV;
> +		goto err_init_phy;

Does this leak priv->pcs_mdiodev?

> +	}
>  
>  	priv->phylink_config.dev = &ndev->dev;
>  	priv->phylink_config.type = PHYLINK_NETDEV;
> @@ -1407,11 +1449,12 @@ static int altera_tse_probe(struct platform_device *pdev)
>  	if (IS_ERR(priv->phylink)) {
>  		dev_err(&pdev->dev, "failed to create phylink\n");
>  		ret = PTR_ERR(priv->phylink);
> -		goto err_init_phy;
> +		goto err_pcs;

Does this leak priv->pcs ?

>  	}
>  
>  	return 0;
> -
> +err_pcs:
> +	mdio_device_free(priv->pcs_mdiodev);
>  err_init_phy:
>  	unregister_netdev(ndev);
>  err_register_netdev:
> @@ -1433,6 +1476,8 @@ static int altera_tse_remove(struct platform_device *pdev)
>  	altera_tse_mdio_destroy(ndev);
>  	unregister_netdev(ndev);
>  	phylink_destroy(priv->phylink);
> +	mdio_device_free(priv->pcs_mdiodev);
> +
>  	free_netdev(ndev);
>  
>  	return 0;
> diff --git a/include/linux/mdio/mdio-regmap.h b/include/linux/mdio/mdio-regmap.h
> index b8508f152552..679d9069846b 100644
> --- a/include/linux/mdio/mdio-regmap.h
> +++ b/include/linux/mdio/mdio-regmap.h
> @@ -7,6 +7,8 @@
>  #ifndef MDIO_REGMAP_H
>  #define MDIO_REGMAP_H
>  
> +#include <linux/phy.h>
> +
>  struct device;
>  struct regmap;
>  

This hunk doesn't seem strictly related to the patch.
Perhaps the include belongs elsewhere.
Or the hunk belongs in another patch.