linux-kernel - Re: [PATCH v5 5/7] PCI: spacemit: Add SpacemiT PCIe host driver

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Message-ID: <120b2f62-25e6-4ea3-9907-230080c61f70@wanadoo.fr>
Date: Sat, 8 Nov 2025 14:00:26 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Alex Elder <elder@...cstar.com>, lpieralisi@...nel.org,
 kwilczynski@...nel.org, mani@...nel.org, robh@...nel.org, bhelgaas@...gle.com
Cc: dlan@...too.org, aurelien@...el32.net, johannes@...felt.com,
 p.zabel@...gutronix.de, christian.bruel@...s.st.com,
 thippeswamy.havalige@....com, krishna.chundru@....qualcomm.com,
 mayank.rana@....qualcomm.com, qiang.yu@....qualcomm.com,
 shradha.t@...sung.com, inochiama@...il.com, guodong@...cstar.com,
 linux-pci@...r.kernel.org, spacemit@...ts.linux.dev,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 5/7] PCI: spacemit: Add SpacemiT PCIe host driver

Le 07/11/2025 à 20:15, Alex Elder a écrit :
> Introduce a driver for the PCIe host controller found in the SpacemiT
> K1 SoC.  The hardware is derived from the Synopsys DesignWare PCIe IP.
> The driver supports three PCIe ports that operate at PCIe gen2 transfer
> rates (5 GT/sec).  The first port uses a combo PHY, which may be
> configured for use for USB 3 instead.
> 
> Signed-off-by: Alex Elder <elder@...cstar.com>
> ---

...

> +static int k1_pcie_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct k1_pcie *k1;
> +	int ret;
> +
> +	k1 = devm_kzalloc(dev, sizeof(*k1), GFP_KERNEL);
> +	if (!k1)
> +		return -ENOMEM;
> +
> +	k1->pmu = syscon_regmap_lookup_by_phandle_args(dev_of_node(dev),
> +						       SYSCON_APMU, 1,
> +						       &k1->pmu_off);
> +	if (IS_ERR(k1->pmu))
> +		return dev_err_probe(dev, PTR_ERR(k1->pmu),
> +				     "failed to lookup PMU registers\n");
> +
> +	k1->link = devm_platform_ioremap_resource_byname(pdev, "link");
> +	if (!k1->link)

if (IS_ERR(k1->link)) ?

> +		return dev_err_probe(dev, -ENOMEM,
> +				     "failed to map \"link\" registers\n");

Message with -ENOMEM are ignored, so a direct return -ENOMEM is less 
verbose and will bhave the same. See [1].

But in this case, I think it should be PTR_ERR(k1->link).

[1]: 
https://elixir.bootlin.com/linux/v6.18-rc2/source/drivers/base/core.c#L5015

> +
> +	k1->pci.dev = dev;
> +	k1->pci.ops = &k1_pcie_ops;
> +	dw_pcie_cap_set(&k1->pci, REQ_RES);
> +
> +	k1->pci.pp.ops = &k1_pcie_host_ops;
> +
> +	/* Hold the PHY in reset until we start the link */
> +	regmap_set_bits(k1->pmu, k1->pmu_off + PCIE_CLK_RESET_CONTROL,
> +			APP_HOLD_PHY_RST);
> +
> +	ret = devm_regulator_get_enable(dev, "vpcie3v3");
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "failed to get \"vpcie3v3\" supply\n");
> +
> +	pm_runtime_set_active(dev);
> +	pm_runtime_no_callbacks(dev);
> +	devm_pm_runtime_enable(dev);
> +
> +	platform_set_drvdata(pdev, k1);
> +
> +	ret = k1_pcie_parse_port(k1);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to parse root port\n");
> +
> +	ret = dw_pcie_host_init(&k1->pci.pp);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to initialize host\n");
> +
> +	return 0;
> +}

...

> +static const struct of_device_id k1_pcie_of_match_table[] = {
> +	{ .compatible = "spacemit,k1-pcie", },
> +	{ },

Unneeded trainling comma after a terminator.

> +};
> +
> +static struct platform_driver k1_pcie_driver = {
> +	.probe	= k1_pcie_probe,
> +	.remove	= k1_pcie_remove,
> +	.driver = {
> +		.name			= "spacemit-k1-pcie",
> +		.of_match_table		= k1_pcie_of_match_table,
> +		.probe_type		= PROBE_PREFER_ASYNCHRONOUS,
> +	},
> +};
> +module_platform_driver(k1_pcie_driver);