netdev - Re: [PATCH 2/4] phy: s32g: Add serdes subsystem phy

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Message-ID: <aXtB0QcVOkE_hhny@shell.armlinux.org.uk>
Date: Thu, 29 Jan 2026 11:17:37 +0000
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: vkoul@...nel.org, neil.armstrong@...aro.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, ciprianmarian.costea@....nxp.com, s32@....com,
	p.zabel@...gutronix.de, ghennadi.procopciuc@....com,
	bogdan-gabriel.roman@....com, Ionut.Vicovan@....com,
	alexandru-catalin.ionita@....com, linux-phy@...ts.infradead.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, netdev@...r.kernel.org,
	Frank.li@....com
Subject: Re: [PATCH 2/4] phy: s32g: Add serdes subsystem phy

On Mon, Jan 26, 2026 at 10:21:57AM +0100, Vincent Guittot wrote:
> +/*
> + * Until now, there is no generic way to describe and set PCIe clock mode.
> + * PCIe controller uses the default CRNS = 0 mode.
> + */
> +enum pcie_phy_mode {
> +	CRNS = 0, /* Common Reference Clock, No Spread Spectrum */
> +	CRSS = 1, /* Common Reference Clock, Spread Spectrum */
> +	SRNS = 2, /* Separate Reference Clock, No Spread Spectrum */
> +	SRIS = 3  /* Separate Reference Clock, Spread Spectrum */
> +};

So this is a PCIe thing. If it's part of the driver's API, then it
should be common and not driver-private.

> +static inline bool is_pcie_phy_mode_valid(int mode)
> +{
> +	switch (mode) {
> +	case CRNS:
> +	case CRSS:
> +	case SRNS:
> +	case SRIS:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}

This checks that the submode is one of the PCIe private modes that this
driver wants to see.

> +
> +static int s32g_serdes_phy_set_mode_ext(struct phy *p,
> +					enum phy_mode mode, int submode)
> +{
> +	struct s32g_serdes *serdes = phy_get_drvdata(p);
> +
> +	if (mode == PHY_MODE_PCIE)
> +		return -EINVAL;
> +
> +	if (!is_pcie_phy_mode_valid(submode))
> +		return -EINVAL;

This checks for the PCIe submode, but notice the test immediately
above. PCIE mode is being rejected. So, this driver supports
everything else but PCIe.

That doesn't seem right.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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