Re: [PATCH 3/3] net: stmicro: imx: set TX_CLK direction in RMII mode

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 22/04/2024 10:46, 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.
> 
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> ---
>  drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c | 27 +++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c b/drivers/net/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)
>  
> +#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;
>  
> @@ -116,6 +121,18 @@ static int imx93_set_intf_mode(struct plat_stmmacenet_data *plat_dat)
>  		break;
>  	case PHY_INTERFACE_MODE_RMII:
>  		val = 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);
> +		else
> +			dev_warn(dwmac->dev, "TX_CLK can't be set to output mode.\n");
> +
>  		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, struct device *dev)
>  			dev_err(dev, "Can't get intf mode reg offset (%d)\n", err);
>  			return err;
>  		}
> +
> +		dwmac->enet_clk_regmap = syscon_regmap_lookup_by_phandle(np, "enet_clk_sel");
> +		if (IS_ERR(dwmac->enet_clk_regmap))
> +			return PTR_ERR(dwmac->enet_clk_regmap);

This looks like breaking ABI. Please test your changes without the DTS.
Does the DTS pass dtbs_check? Does the driver probe correctly with such DTS?

Best regards,
Krzysztof