linux-kernel - Re: [PATCH v3 2/2] ethernet: eswin: Add eic7700 ethernet driver

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Message-ID: <c212c50e-52ae-4330-8e67-792e83ab29e4@lunn.ch>
Date: Thu, 3 Jul 2025 18:12:29 +0200
From: Andrew Lunn <andrew@...n.ch>
To: weishangjuan@...incomputing.com
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
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Subject: Re: [PATCH v3 2/2] ethernet: eswin: Add eic7700 ethernet driver

> +/* Default delay value*/
> +#define EIC7700_DELAY_VALUE0 0x20202020
> +#define EIC7700_DELAY_VALUE1 0x96205A20

We need a better explanation of what is going on here. What do these
numbers mean?

> +	dwc_priv->dly_param_1000m[0] = EIC7700_DELAY_VALUE0;
> +	dwc_priv->dly_param_1000m[1] = EIC7700_DELAY_VALUE1;
> +	dwc_priv->dly_param_1000m[2] = EIC7700_DELAY_VALUE0;
> +	dwc_priv->dly_param_100m[0] = EIC7700_DELAY_VALUE0;
> +	dwc_priv->dly_param_100m[1] = EIC7700_DELAY_VALUE1;
> +	dwc_priv->dly_param_100m[2] = EIC7700_DELAY_VALUE0;
> +	dwc_priv->dly_param_10m[0] = 0x0;
> +	dwc_priv->dly_param_10m[1] = 0x0;
> +	dwc_priv->dly_param_10m[2] = 0x0;

What are the three different values for?

> +
> +	ret = of_property_read_u32(pdev->dev.of_node, "rx-internal-delay-ps",
> +				   &dwc_priv->rx_delay_ps);
> +	if (ret)
> +		dev_dbg(&pdev->dev, "can't get rx-internal-delay-ps, ret(%d).", ret);
> +	else
> +		has_rx_dly = true;
> +
> +	ret = of_property_read_u32(pdev->dev.of_node, "tx-internal-delay-ps",
> +				   &dwc_priv->tx_delay_ps);
> +	if (ret)
> +		dev_dbg(&pdev->dev, "can't get tx-internal-delay-ps, ret(%d).", ret);
> +	else
> +		has_tx_dly = true;
> +	if (has_rx_dly && has_tx_dly)

What if i only to set a TX delay? I want the RX delay to default to
0ps.

{
> +		eic7700_set_delay(dwc_priv->rx_delay_ps, dwc_priv->tx_delay_ps,
> +				  &dwc_priv->dly_param_1000m[1]);
> +		eic7700_set_delay(dwc_priv->rx_delay_ps, dwc_priv->tx_delay_ps,
> +				  &dwc_priv->dly_param_100m[1]);
> +		eic7700_set_delay(dwc_priv->rx_delay_ps, dwc_priv->tx_delay_ps,
> +				  &dwc_priv->dly_param_10m[1]);
> +	} else {
> +		dev_dbg(&pdev->dev, " use default dly\n");

What is the default? It should be 0ps. So there is no point printing
this message.

	Andrew