Re: [PATCH v3 4/5] net: stmmac: add a glue driver for the Amlogic Meson 8b / GXBB DWMAC

Stephen Boyd
2016-08-30T19:19:08Z

On 08/28, Martin Blumenstingl wrote:
> +static int meson8b_init_clk(struct meson8b_dwmac *dwmac)
> +{
> + struct clk_init_data init;
> + int i, ret;
> + struct device *dev = &dwmac->pdev->dev;
> + char clk_name[32];
> + const char *clk_div_parents[1];
> + const char *mux_parent_names[MUX_CLK_NUM_PARENTS];
> + static struct clk_div_table clk_25m_div_table[] = {
> + { .val = 0, .div = 5 },
> + { .val = 1, .div = 10 },
> + { /* sentinel */ },
> + };
> +
> + /* get the mux parents from DT */
> + for (i = 0; i < MUX_CLK_NUM_PARENTS; i++) {
> + char name[16];
> +
> + snprintf(name, sizeof(name), "clkin%d", i);
> + dwmac->m250_mux_parent[i] = devm_clk_get(dev, name);
> + if (IS_ERR(dwmac->m250_mux_parent[i])) {
> + ret = PTR_ERR(dwmac->m250_mux_parent[i]);
> + if (ret != -EPROBE_DEFER)
> + dev_err(dev, "Missing clock %s\n", name);
> + return ret;
> + }
> +
> + mux_parent_names[i] =
> + __clk_get_name(dwmac->m250_mux_parent[i]);
> + }
> +
> + /* create the m250_mux */
> + snprintf(clk_name, sizeof(clk_name), "%s#m250_sel", dev_name(dev));
> + init.name = clk_name;
> + init.ops = &clk_mux_ops;
> + init.flags = CLK_IS_BASIC;

Please don't use this flag unless you need it.

> + init.parent_names = mux_parent_names;
> + init.num_parents = MUX_CLK_NUM_PARENTS;
> +
> + dwmac->m250_mux.reg = dwmac->regs + PRG_ETH0;
> + dwmac->m250_mux.shift = PRG_ETH0_CLK_M250_SEL_SHIFT;
> + dwmac->m250_mux.mask = PRG_ETH0_CLK_M250_SEL_MASK;
> + dwmac->m250_mux.flags = 0;
> + dwmac->m250_mux.table = NULL;
> + dwmac->m250_mux.hw.init = &init;
> +
> + dwmac->m250_mux_clk = devm_clk_register(dev, &dwmac->m250_mux.hw);
> + if (WARN_ON(PTR_ERR_OR_ZERO(dwmac->m250_mux_clk)))

Why not if(WARN_ON(IS_ERR())? The OR_ZERO part seems confusing.

> + return PTR_ERR(dwmac->m250_mux_clk);
> +
> + /* create the m250_div */
> + snprintf(clk_name, sizeof(clk_name), "%s#m250_div", dev_name(dev));
> + init.name = devm_kstrdup(dev, clk_name, GFP_KERNEL);
> + init.ops = &clk_divider_ops;
> + init.flags = CLK_IS_BASIC | CLK_SET_RATE_PARENT;
> + clk_div_parents[0] = __clk_get_name(dwmac->m250_mux_clk);
> + init.parent_names = clk_div_parents;
> + init.num_parents = ARRAY_SIZE(clk_div_parents);
> +
> + dwmac->m250_div.reg = dwmac->regs + PRG_ETH0;
> + dwmac->m250_div.shift = PRG_ETH0_CLK_M250_DIV_SHIFT;
> + dwmac->m250_div.width = PRG_ETH0_CLK_M250_DIV_WIDTH;
> + dwmac->m250_div.hw.init = &init;
> + dwmac->m250_div.flags = CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ALLOW_ZERO;
> +
> + dwmac->m250_div_clk = devm_clk_register(dev, &dwmac->m250_div.hw);

We've been trying to move away from devm_clk_register() to
devm_clk_hw_register() so that clk providers aren't also clk
consumers. Obviously in this case this driver is a provider and a
consumer, so this isn't as important. Kevin did something similar
in the mmc driver, so I'll reiterate what I said on that patch.
Perhaps we should make __clk_create_clk() into a real clk
provider API so that we can use devm_clk_hw_register() here and
then generate a clk for this device. That would allow us to have
proper consumer tracking without relying on the clk that is
returned from clk_register() (the intent is to make that clk
instance internal to the framework).

> + if (WARN_ON(PTR_ERR_OR_ZERO(dwmac->m250_div_clk)))
> + return PTR_ERR(dwmac->m250_div_clk);
> +
> + /* create the m25_div */
> + snprintf(clk_name, sizeof(clk_name), "%s#m25_div", dev_name(dev));
> + init.name = devm_kstrdup(dev, clk_name, GFP_KERNEL);
> + init.ops = &clk_divider_ops;
> + init.flags = CLK_IS_BASIC | CLK_SET_RATE_PARENT;
> + clk_div_parents[0] = __clk_get_name(dwmac->m250_div_clk);
> + init.parent_names = clk_div_parents;
> + init.num_parents = ARRAY_SIZE(clk_div_parents);
> +
> + dwmac->m25_div.reg = dwmac->regs + PRG_ETH0;
> + dwmac->m25_div.shift = PRG_ETH0_CLK_M25_DIV_SHIFT;
> + dwmac->m25_div.width = PRG_ETH0_CLK_M25_DIV_WIDTH;
> + dwmac->m25_div.table = clk_25m_div_table;
> + dwmac->m25_div.hw.init = &init;
> + dwmac->m25_div.flags = CLK_DIVIDER_ALLOW_ZERO;
> +
> + dwmac->m25_div_clk = devm_clk_register(dev, &dwmac->m25_div.hw);
> + if (WARN_ON(PTR_ERR_OR_ZERO(dwmac->m25_div_clk)))
> + return PTR_ERR(dwmac->m25_div_clk);
> +
> + return 0;

This could be return WARN_ON(PTR_ERR_OR_ZERO(...))

> +
> +static int meson8b_dwmac_probe(struct platform_device *pdev)
> +{
> + struct plat_stmmacenet_data *plat_dat;
> + struct stmmac_resources stmmac_res;
> + struct resource *res;
> + struct meson8b_dwmac *dwmac;
> + int ret;
> +
> + ret = stmmac_get_platform_resources(pdev, &stmmac_res);
> + if (ret)
> + return ret;
> +
> + plat_dat = stmmac_probe_config_dt(pdev, &stmmac_res.mac);
> + if (IS_ERR(plat_dat))
> + return PTR_ERR(plat_dat);
> +
> + dwmac = devm_kzalloc(&pdev->dev, sizeof(*dwmac), GFP_KERNEL);
> + if (!dwmac)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + if (!res)
> + return -ENODEV;
> +

You can drop the above two lines and just call
devm_ioremap_resource().

> + dwmac->regs = devm_ioremap_resource(&pdev->dev, res);

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