linux-kernel - Re: [PATCH 2/3] mmc: sdhci-dwcmshc: Add Canaan K230 DWCMSHC controller support

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Message-ID: <aYb7m+ioAmqXFhWX@duge-virtual-machine>
Date: Sat, 7 Feb 2026 16:45:15 +0800
From: Jiayu Du <jiayu.riscv@...c.iscas.ac.cn>
To: Krzysztof Kozlowski <krzk@...nel.org>, ulf.hansson@...aro.org,
	adrian.hunter@...el.com, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org
Cc: pjw@...nel.org, palmer@...belt.com, aou@...s.berkeley.edu,
	linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	gaohan@...as.ac.cn, me@...ao.cc
Subject: Re: [PATCH 2/3] mmc: sdhci-dwcmshc: Add Canaan K230 DWCMSHC
 controller support

On Fri, Feb 06, 2026 at 02:26:40PM +0100, Krzysztof Kozlowski wrote:
> On 04/02/2026 09:29, Jiayu Du wrote:
> > +static int dwcmshc_k230_init(struct device *dev, struct sdhci_host *host,
> > +			     struct dwcmshc_priv *dwc_priv)
> > +{
> > +	static const char * const clk_ids[] = {"base", "timer", "ahb"};
> > +	struct device_node *usb_phy_node;
> > +	struct k230_priv *k230_priv;
> > +	u32 data;
> > +	int ret;
> > +
> > +	k230_priv = devm_kzalloc(dev, sizeof(struct k230_priv), GFP_KERNEL);
> > +	if (!k230_priv)
> > +		return -ENOMEM;
> > +	dwc_priv->priv = k230_priv;
> > +
> > +	usb_phy_node = of_find_compatible_node(NULL, NULL, "canaan,k230-usb-phy");
> 
> Hm? You should use phandles, not look for various nodes.

Only one usbphy node has the canaan, k230-usb-phy compatibility.
So in this situation, is it ok to continue using of_find_compatible_node?

> > +	if (!usb_phy_node) {
> 
> Please follow Linux coding style.

I will fix it in next version.

> > +		return dev_err_probe(dev, -ENODEV,
> > +				     "Failed to find k230-usb-phy node\n");
> > +	}
> > +
> > +	k230_priv->hi_sys_regmap = device_node_to_regmap(usb_phy_node);
> > +	of_node_put(usb_phy_node);
> > +	if (IS_ERR(k230_priv->hi_sys_regmap)) {
> > +		return dev_err_probe(dev, PTR_ERR(k230_priv->hi_sys_regmap),
> > +				     "Failed to get k230-usb-phy regmap\n");
> > +	}
> > +
> > +	ret = dwcmshc_get_enable_other_clks(mmc_dev(host->mmc), dwc_priv,
> > +					    ARRAY_SIZE(clk_ids), clk_ids);
> > +	if (ret) {
> > +		return dev_err_probe(dev, ret,
> > +				     "Failed to get/enable k230 mmc other clocks\n");
> > +	}
> > +
> > +	if (of_device_is_compatible(dev->of_node, "canaan,k230-sdio")) {
> 
> Driver match data is for this.

What you mean is that I shouldn't use of_find_compatible_node, but I can
use device_get_match_data instead? Then I can continue to distinguish
between SDIO and eMMC to do parameter configuration

Or do you mean that I should put the parameters to be adjusted into the
pdata structure? But currently, the dwcmshc structure is not suitable for
containing vendor-specific properties.

Regards,
Jiayu Du
> 
> Best regards,
> Krzysztof