Re: [PATCH v3 net 2/2] net: stmmac: dwmac-imx: pause the TXC clock in fixed-link

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 31.07.2023 11:19:29, Shenwei Wang wrote:
> When using a fixed-link setup, certain devices like the SJA1105 require a
> small pause in the TXC clock line to enable their internal tunable
> delay line (TDL).
> 
> To satisfy this requirement, this patch temporarily disables the TX clock,
> and restarts it after a required period. This provides the required
> silent interval on the clock line for SJA1105 to complete the frequency
> transition and enable the internal TDLs.
> 
> So far we have only enabled this feature on the i.MX93 platform.
> 
> Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
> Reviewed-by: Frank Li <frank.li@nxp.com>
> ---
>  .../net/ethernet/stmicro/stmmac/dwmac-imx.c   | 42 +++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> index 53ee5a42c071..2e4173d099f3 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
> @@ -32,6 +32,7 @@
>  #define GPR_ENET_QOS_RGMII_EN		(0x1 << 21)
>  
>  #define MX93_GPR_ENET_QOS_INTF_MODE_MASK	GENMASK(3, 0)
> +#define MX93_GPR_ENET_QOS_INTF_MASK		GENMASK(3, 1)
>  #define MX93_GPR_ENET_QOS_INTF_SEL_MII		(0x0 << 1)
>  #define MX93_GPR_ENET_QOS_INTF_SEL_RMII		(0x4 << 1)
>  #define MX93_GPR_ENET_QOS_INTF_SEL_RGMII	(0x1 << 1)
> @@ -40,6 +41,7 @@
>  #define DMA_BUS_MODE			0x00001000
>  #define DMA_BUS_MODE_SFT_RESET		(0x1 << 0)
>  #define RMII_RESET_SPEED		(0x3 << 14)
> +#define CTRL_SPEED_MASK			GENMASK(15, 14)
>  
>  struct imx_dwmac_ops {
>  	u32 addr_width;
> @@ -56,6 +58,7 @@ struct imx_priv_data {
>  	struct regmap *intf_regmap;
>  	u32 intf_reg_off;
>  	bool rmii_refclk_ext;
> +	void __iomem *base_addr;
>  
>  	const struct imx_dwmac_ops *ops;
>  	struct plat_stmmacenet_data *plat_dat;
> @@ -212,6 +215,42 @@ static void imx_dwmac_fix_speed(void *priv, uint speed, uint mode)
>  		dev_err(dwmac->dev, "failed to set tx rate %lu\n", rate);
>  }
>  
> +static void imx_dwmac_fix_speed_mx93(void *priv, uint speed, uint mode)
> +{
> +	struct imx_priv_data *dwmac = priv;
> +	int ctrl, old_ctrl, iface;

regmap_read() wants a pointer to an "unsigned int".

> +
> +	imx_dwmac_fix_speed(priv, speed, mode);
> +
> +	if (!dwmac || mode != MLO_AN_FIXED)
> +		return;
> +
> +	if (regmap_read(dwmac->intf_regmap, dwmac->intf_reg_off, &iface))
> +		return;
> +
> +	iface &= MX93_GPR_ENET_QOS_INTF_MASK;
> +	if (iface != MX93_GPR_ENET_QOS_INTF_SEL_RGMII)
> +		return;
> +
> +	old_ctrl = readl(dwmac->base_addr + MAC_CTRL_REG);
> +	ctrl = old_ctrl & ~CTRL_SPEED_MASK;
> +	regmap_update_bits(dwmac->intf_regmap, dwmac->intf_reg_off,
> +			   MX93_GPR_ENET_QOS_INTF_MODE_MASK, 0);
> +	writel(ctrl, dwmac->base_addr + MAC_CTRL_REG);
> +
> +	/* Ensure the settings for CTRL are applied and avoid CPU/Compiler
> +	 * reordering.
> +	 */
> +	wmb();
> +
> +	usleep_range(10, 20);
> +	iface |= MX93_GPR_ENET_QOS_CLK_GEN_EN;
> +	regmap_update_bits(dwmac->intf_regmap, dwmac->intf_reg_off,
> +			   MX93_GPR_ENET_QOS_INTF_MODE_MASK, iface);
> +
> +	writel(old_ctrl, dwmac->base_addr + MAC_CTRL_REG);
> +}

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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