Hi Niklas, Andrew,
On Thu, May 9, 2024 at 11:10 PM Niklas Söderlund
<niklas.soderlund+renesas@xxxxxxxxxxxx> wrote:
> Add initial support for Renesas Ethernet-TSN End-station device of R-Car
> V4H. The Ethernet End-station can connect to an Ethernet network using a
> 10 Mbps, 100 Mbps, or 1 Gbps full-duplex link via MII/GMII/RMII/RGMII.
> Depending on the connected PHY.
>
> The driver supports Rx checksum and offload and hardware timestamps.
>
> While full power management and suspend/resume is not yet supported the
> driver enables runtime PM in order to enable the module clock. While
> explicit clock management using clk_enable() would suffice for the
> supported SoC, the module could be reused on SoCs where the module is
> part of a power domain.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
> * Changes since v4
> - Enable GPOUT_RDM and GPOUT_TDM delays depending on phy-mode.
Thanks for the update!
> +static void rtsn_set_delay_mode(struct rtsn_private *priv)
> +{
> + u32 val = 0;
> +
> + /* The MAC is capable of applying a delay on both Rx and Tx. Each
> + * delay can either be on or off, there is no way to set its length.
> + *
> + * The exact delay applied depends on electric characteristics of the
> + * board. The datasheet describes a typical Rx delay of 1800 ps and a
> + * typical Tx delay of 2000 ps.
> + *
> + * There are boards where the RTSN device is used together with PHYs
> + * who do not support a large enough internal delays to function. These
> + * boards depends on the MAC applying these inexact delays.
> + */
> +
> + /* If the phy-mode is rgmii or rgmii-rxid apply Rx delay on the MAC */
> + if (priv->iface == PHY_INTERFACE_MODE_RGMII_ID ||
> + priv->iface == PHY_INTERFACE_MODE_RGMII_RXID)
> + val |= GPOUT_RDM;
> +
> + /* If the phy-mode is rgmii or rgmii-txid apply Tx delay on the MAC */
> + if (priv->iface == PHY_INTERFACE_MODE_RGMII_ID ||
> + priv->iface == PHY_INTERFACE_MODE_RGMII_TXID)
> + val |= GPOUT_TDM;
> +
> + rtsn_write(priv, GPOUT, val);
> +}
> +static int rtsn_phy_init(struct rtsn_private *priv)
> +{
> + struct device_node *np = priv->ndev->dev.parent->of_node;
> + struct phy_device *phydev;
> + struct device_node *phy;
> + phy_interface_t iface;
> +
> + /* Delays, if any, are applied by the MAC. Mask RGMII mode passed to the
> + * PHY to avoid it also adding the delay.
> + */
> + switch (priv->iface) {
> + case PHY_INTERFACE_MODE_RGMII:
> + case PHY_INTERFACE_MODE_RGMII_ID:
> + case PHY_INTERFACE_MODE_RGMII_RXID:
> + case PHY_INTERFACE_MODE_RGMII_TXID:
> + iface = PHY_INTERFACE_MODE_RGMII;
> + break;
> + default:
> + iface = priv->iface;
> + break;
> + }
This introduces the same issues (the "workaround" state below) we had
with ravb before.
9b23203c32ee02cd ("ravb: Mask PHY mode to avoid inserting delays twice")
was the workaround,
a6f51f2efa742df0 ("ravb: Add support for explicit internal clock delay
configuration")
was the final fix.
Do we really want to repeat that mistake?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
