linux-kernel - Re: [PATCH net-next v2 13/13] net: dsa: add driver for MaxLinear GSW1xx switch family

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Message-ID: <43f20230-1e13-4952-8069-bbcb9d966a0f@bootlin.com>
Date: Sat, 25 Oct 2025 18:43:12 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Daniel Golle <daniel@...rotopia.org>, Hauke Mehrtens <hauke@...ke-m.de>,
 Andrew Lunn <andrew@...n.ch>, Vladimir Oltean <olteanv@...il.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Simon Horman <horms@...nel.org>,
 Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Andreas Schirm <andreas.schirm@...mens.com>,
 Lukas Stockmann <lukas.stockmann@...mens.com>,
 Alexander Sverdlin <alexander.sverdlin@...mens.com>,
 Peter Christen <peter.christen@...mens.com>,
 Avinash Jayaraman <ajayaraman@...linear.com>, Bing tao Xu
 <bxu@...linear.com>, Liang Xu <lxu@...linear.com>,
 Juraj Povazanec <jpovazanec@...linear.com>,
 "Fanni (Fang-Yi) Chan" <fchan@...linear.com>,
 "Benny (Ying-Tsan) Weng" <yweng@...linear.com>,
 "Livia M. Rosu" <lrosu@...linear.com>, John Crispin <john@...ozen.org>
Subject: Re: [PATCH net-next v2 13/13] net: dsa: add driver for MaxLinear
 GSW1xx switch family

Hi Daniel,

On 25/10/2025 16:51, Daniel Golle wrote:
> Add driver for the MaxLinear GSW1xx family of Ethernet switch ICs which
> are based on the same IP as the Lantiq/Intel GSWIP found in the Lantiq VR9
> and Intel GRX MIPS router SoCs. The main difference is that instead of
> using memory-mapped I/O to communicate with the host CPU these ICs are
> connected via MDIO (or SPI, which isn't supported by this driver).
> Implement the regmap API to access the switch registers over MDIO to allow
> reusing lantiq_gswip_common for all core functionality.
> 
> The GSW1xx also comes with a SerDes port capable of 1000Base-X, SGMII and
> 2500Base-X, which can either be used to connect an external PHY or SFP
> cage, or as the CPU port. Support for the SerDes interface is implemented
> in this driver using the phylink_pcs interface.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---

[...]

> +static int gsw1xx_sgmii_pcs_config(struct phylink_pcs *pcs,
> +				   unsigned int neg_mode,
> +				   phy_interface_t interface,
> +				   const unsigned long *advertising,
> +				   bool permit_pause_to_mac)
> +{
> +	struct gsw1xx_priv *priv = sgmii_pcs_to_gsw1xx(pcs);
> +	bool sgmii_mac_mode = dsa_is_user_port(priv->gswip.ds, GSW1XX_SGMII_PORT);
> +	u16 txaneg, anegctl, val, nco_ctrl;
> +	int ret;
> +
> +	/* Assert and deassert SGMII shell reset */
> +	ret = regmap_set_bits(priv->shell, GSW1XX_SHELL_RST_REQ,
> +			      GSW1XX_RST_REQ_SGMII_SHELL);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_clear_bits(priv->shell, GSW1XX_SHELL_RST_REQ,
> +				GSW1XX_RST_REQ_SGMII_SHELL);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Hardware Bringup FSM Enable  */
> +	ret = regmap_write(priv->sgmii, GSW1XX_SGMII_PHY_HWBU_CTRL,
> +			   GSW1XX_SGMII_PHY_HWBU_CTRL_EN_HWBU_FSM |
> +			   GSW1XX_SGMII_PHY_HWBU_CTRL_HW_FSM_EN);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Configure SGMII PHY Receiver */
> +	val = FIELD_PREP(GSW1XX_SGMII_PHY_RX0_CFG2_EQ,
> +			 GSW1XX_SGMII_PHY_RX0_CFG2_EQ_DEF) |
> +	      GSW1XX_SGMII_PHY_RX0_CFG2_LOS_EN |
> +	      GSW1XX_SGMII_PHY_RX0_CFG2_TERM_EN |
> +	      FIELD_PREP(GSW1XX_SGMII_PHY_RX0_CFG2_FILT_CNT,
> +			 GSW1XX_SGMII_PHY_RX0_CFG2_FILT_CNT_DEF);
> +
> +	// if (!priv->dts.sgmii_rx_invert)
> +		val |= GSW1XX_SGMII_PHY_RX0_CFG2_INVERT;

There's a leftover commented-out line here :)

Maxime