Re: [PATCH net-next 3/3] net: stmmac: add glue layer for T-HEAD TH1520 SoC

[Simon Horman]

On Sun, Aug 20, 2023 at 08:02:13PM +0800, Jisheng Zhang wrote:
> Add dwmac glue driver to support the dwmac on the T-HEAD TH1520 SoC.
> 
> Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxx>

...

> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-thead.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-thead.c

...

> +static void thead_dwmac_fix_speed(void *priv, unsigned int speed, unsigned int mode)
> +{
> +	struct thead_dwmac *dwmac = priv;
> +	struct plat_stmmacenet_data *plat = dwmac->plat;
> +	unsigned long rate;
> +	u32 div;
> +
> +	switch (plat->interface) {
> +	/* For MII, rxc/txc is provided by phy */
> +	case PHY_INTERFACE_MODE_MII:
> +		return;
> +
> +	case PHY_INTERFACE_MODE_RGMII:
> +	case PHY_INTERFACE_MODE_RGMII_ID:
> +	case PHY_INTERFACE_MODE_RGMII_RXID:
> +	case PHY_INTERFACE_MODE_RGMII_TXID:
> +		rate = clk_get_rate(plat->stmmac_clk);
> +		if (!rate || rate % GMAC_GMII_RGMII_RATE != 0 ||
> +		    rate % GMAC_MII_RATE != 0) {
> +			dev_err(dwmac->dev, "invalid gmac rate %ld\n", rate);
> +			return;
> +		}
> +
> +		regmap_update_bits(dwmac->apb_regmap, GMAC_PLLCLK_DIV, GMAC_PLLCLK_DIV_EN, 0);
> +
> +		switch (speed) {
> +		case SPEED_1000:
> +			div = rate / GMAC_GMII_RGMII_RATE;
> +			break;
> +		case SPEED_100:
> +			div = rate / GMAC_MII_RATE;
> +			break;
> +		case SPEED_10:
> +			div = rate * 10 / GMAC_MII_RATE;
> +			break;
> +		default:
> +			dev_err(dwmac->dev, "invalid speed %u\n", speed);
> +			break;

Hi Jisheng Zhang,

In this case, div is not initialised, but it is used a few
lines below. Perhaps the function should return here?

As flagged by clang-16 (W=1) and Smatch.

> +		}
> +		regmap_update_bits(dwmac->apb_regmap, GMAC_PLLCLK_DIV,
> +				   GMAC_PLLCLK_DIV_MASK, GMAC_PLLCLK_DIV_NUM(div));
> +
> +		regmap_update_bits(dwmac->apb_regmap, GMAC_PLLCLK_DIV,
> +				   GMAC_PLLCLK_DIV_EN, GMAC_PLLCLK_DIV_EN);
> +		break;
> +	default:
> +		dev_err(dwmac->dev, "unsupported phy interface %d\n",
> +			plat->interface);
> +		return;
> +	}
> +}

...