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Date: Mon, 22 Apr 2024 11:04:00 +0200
From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>, 
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, 
	Paolo Abeni <pabeni@redhat.com>, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Shawn Guo <shawnguo@kernel.org>, Sascha Hauer <s.hauer@pengutronix.de>, 
	Pengutronix Kernel Team <kernel@pengutronix.de>, Fabio Estevam <festevam@gmail.com>, 
	Clark Wang <xiaoning.wang@nxp.com>, Linux Team <linux-imx@nxp.com>, 
	Alexandre Torgue <alexandre.torgue@foss.st.com>, Jose Abreu <joabreu@synopsys.com>, 
	Maxime Coquelin <mcoquelin.stm32@gmail.com>, imx@lists.linux.dev, devicetree@vger.kernel.org, 
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/3] net: stmicro: imx: set TX_CLK direction in RMII mode
Message-ID: <20240422-vigilant-chupacabra-of-lightning-f11220-mkl@pengutronix.de>
References: <20240422-v6-9-topic-imx93-eqos-rmii-v1-0-30151fca43d2@pengutronix.de>
 <20240422-v6-9-topic-imx93-eqos-rmii-v1-3-30151fca43d2@pengutronix.de>
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On 22.04.2024 10:46:19, Steffen Trumtrar wrote:
> In case of RMII connection, the TX_CLK must be set to output direction.
> Parse the register and offset from the devicetree and set the direction
> of the TX_CLK when the property was provided.
>=20
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> ---
>  drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c | 27 +++++++++++++++++++=
++++++
>  1 file changed, 27 insertions(+)
>=20
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c b/drivers/ne=
t/ethernet/stmicro/stmmac/dwmac-imx.c
> index 6b65420e11b5c..0fc81a626a664 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> @@ -37,6 +37,9 @@
>  #define MX93_GPR_ENET_QOS_INTF_SEL_RGMII	(0x1 << 1)
>  #define MX93_GPR_ENET_QOS_CLK_GEN_EN		(0x1 << 0)
> =20
> +#define MX93_GPR_ENET_QOS_TX_CLK_SEL_MASK	GENMASK(1, 1)
> +#define MX93_GPR_ENET_QOS_TX_CLK_SEL		(0x1 << 1)
> +
>  #define DMA_BUS_MODE			0x00001000
>  #define DMA_BUS_MODE_SFT_RESET		(0x1 << 0)
>  #define RMII_RESET_SPEED		(0x3 << 14)
> @@ -57,7 +60,9 @@ struct imx_priv_data {
>  	struct clk *clk_tx;
>  	struct clk *clk_mem;
>  	struct regmap *intf_regmap;
> +	struct regmap *enet_clk_regmap;
>  	u32 intf_reg_off;
> +	u32 enet_clk_reg_off;
>  	bool rmii_refclk_ext;
>  	void __iomem *base_addr;
> =20
> @@ -116,6 +121,18 @@ static int imx93_set_intf_mode(struct plat_stmmacene=
t_data *plat_dat)
>  		break;
>  	case PHY_INTERFACE_MODE_RMII:
>  		val =3D MX93_GPR_ENET_QOS_INTF_SEL_RMII;
> +
> +		/* According to NXP AN14149, the direction of the
> +		 * TX_CLK must be set to output in RMII mode.
> +		 */
> +		if (dwmac->enet_clk_regmap)
> +			regmap_update_bits(dwmac->enet_clk_regmap,
> +					   dwmac->enet_clk_reg_off,
> +					   MX93_GPR_ENET_QOS_TX_CLK_SEL_MASK,
> +					   MX93_GPR_ENET_QOS_TX_CLK_SEL);

Please add error handling.

> +		else
> +			dev_warn(dwmac->dev, "TX_CLK can't be set to output mode.\n");

As far as I understand the AN14149, setting the TX_CLK_SEL is mandatory
for PHY_INTERFACE_MODE_RMII. IMHO this should be error, shouldn't it?

> +
>  		break;
>  	case PHY_INTERFACE_MODE_RGMII:
>  	case PHY_INTERFACE_MODE_RGMII_ID:
> @@ -310,6 +327,16 @@ imx_dwmac_parse_dt(struct imx_priv_data *dwmac, stru=
ct device *dev)
>  			dev_err(dev, "Can't get intf mode reg offset (%d)\n", err);
>  			return err;
>  		}
> +
> +		dwmac->enet_clk_regmap =3D syscon_regmap_lookup_by_phandle(np, "enet_c=
lk_sel");
> +		if (IS_ERR(dwmac->enet_clk_regmap))
> +			return PTR_ERR(dwmac->enet_clk_regmap);
> +
> +		err =3D of_property_read_u32_index(np, "enet_clk_sel", 1, &dwmac->enet=
_clk_reg_off);
> +		if (err) {
> +			dev_err(dev, "Can't get enet clk sel reg offset (%d)\n", err);
> +			return err;
> +		}

regards,
Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung N=C3=BCrnberg              | Phone: +49-5121-206917-129 |
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