Re: [RFC PATCH net-next 4/4] net: dp83869: Add RGMII internal delay configuration

From: Andrew Lunn
Date: Sat May 23 2020 - 10:59:19 EST


On Thu, May 21, 2020 at 12:48:34PM -0500, Dan Murphy wrote:
> Add RGMII internal delay configuration for Rx and Tx.
>
> Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
> ---
> drivers/net/phy/dp83869.c | 101 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 101 insertions(+)
>
> diff --git a/drivers/net/phy/dp83869.c b/drivers/net/phy/dp83869.c
> index cfb22a21a2e6..40c34fefffe4 100644
> --- a/drivers/net/phy/dp83869.c
> +++ b/drivers/net/phy/dp83869.c
> @@ -99,6 +99,14 @@
> #define DP83869_OP_MODE_MII BIT(5)
> #define DP83869_SGMII_RGMII_BRIDGE BIT(6)
>
> +/* RGMIIDCTL bits */
> +#define DP83869_RGMII_TX_CLK_DELAY_SHIFT 4
> +#define DP83869_RGMII_CLK_DELAY_INV 0
> +
> +static int dp83869_internal_delay[] = {250, 500, 750, 1000, 1250, 1500, 1750,
> + 2000, 2250, 2500, 2750, 3000, 3250,
> + 3500, 3750, 4000};
> +
> enum {
> DP83869_PORT_MIRRORING_KEEP,
> DP83869_PORT_MIRRORING_EN,
> @@ -108,6 +116,8 @@ enum {
> struct dp83869_private {
> int tx_fifo_depth;
> int rx_fifo_depth;
> + u32 rx_id_delay;
> + u32 tx_id_delay;
> int io_impedance;
> int port_mirroring;
> bool rxctrl_strap_quirk;
> @@ -182,6 +192,7 @@ static int dp83869_of_init(struct phy_device *phydev)
> struct dp83869_private *dp83869 = phydev->priv;
> struct device *dev = &phydev->mdio.dev;
> struct device_node *of_node = dev->of_node;
> + int delay_size = ARRAY_SIZE(dp83869_internal_delay);
> int ret;
>
> if (!of_node)
> @@ -232,6 +243,26 @@ static int dp83869_of_init(struct phy_device *phydev)
> &dp83869->tx_fifo_depth))
> dp83869->tx_fifo_depth = DP83869_PHYCR_FIFO_DEPTH_4_B_NIB;
>
> + dp83869->rx_id_delay = DP83869_RGMII_CLK_DELAY_INV;
> + ret = of_property_read_u32(of_node, "rx-internal-delay",
> + &dp83869->rx_id_delay);
> + if (!ret && dp83869->rx_id_delay > dp83869_internal_delay[delay_size]) {
> + phydev_err(phydev,
> + "rx-internal-delay value of %u out of range\n",
> + dp83869->rx_id_delay);
> + return -EINVAL;
> + }

Hi Dan

Seems like the helper should be doing the range check, and printing
the message. It should be common to all PHY drivers using delays
looked up in a list.

I also wonder about putting the of_property_read_u32 inside a
helper. Something like

of_get_phy_rgmii_delays(struct device_node *np, phy_interface_t interface,
u32 *rx_delay, u32 *tx_delay)

And maybe a third helper which combines phy_get_delay_index() and
of_get_phy_rgmii_delays().

> +static int dp83869_verify_rgmii_cfg(struct phy_device *phydev)
> +{
> + struct dp83869_private *dp83869 = phydev->priv;
> +
> + /* RX delay *must* be specified if internal delay of RX is used. */

No. As i said last time, default to 2ns, if there is no specific delay
value in DT.

Andrew