netdev - Re: [PATCH net-next v4 5/5] ravb: Add support for explicit internal clock delay configuration

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Date:   Thu, 17 Sep 2020 13:49:54 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
CC:     Rob Herring <robh+dt@...nel.org>,
        Sergei Shtylyov <sergei.shtylyov@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Magnus Damm <magnus.damm@...il.com>, <netdev@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v4 5/5] ravb: Add support for explicit internal
 clock delay configuration

Geert

On 9/17/20 8:57 AM, Geert Uytterhoeven wrote:
> Some EtherAVB variants support internal clock delay configuration, which
> can add larger delays than the delays that are typically supported by
> the PHY (using an "rgmii-*id" PHY mode, and/or "[rt]xc-skew-ps"
> properties).
>
> Historically, the EtherAVB driver configured these delays based on the
> "rgmii-*id" PHY mode.  This caused issues with PHY drivers that
> implement PHY internal delays properly[1].  Hence a backwards-compatible
> workaround was added by masking the PHY mode[2].
>
> Add proper support for explicit configuration of the MAC internal clock
> delays using the new "[rt]x-internal-delay-ps" properties.
> Fall back to the old handling if none of these properties is present.
>
> [1] Commit bcf3440c6dd78bfe ("net: phy: micrel: add phy-mode support for
>      the KSZ9031 PHY")
> [2] Commit 9b23203c32ee02cd ("ravb: Mask PHY mode to avoid inserting
>      delays twice").
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> Reviewed-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
> Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> ---
> v4:
>    - Add Reviewed-by,
>
> v3:
>    - No changes,
>
> v2:
>    - Add Reviewed-by,
>    - Split long line,
>    - Replace "renesas,[rt]xc-delay-ps" by "[rt]x-internal-delay-ps",
>    - Use 1 instead of true when assigning to a single-bit bitfield.
> ---
>   drivers/net/ethernet/renesas/ravb.h      |  1 +
>   drivers/net/ethernet/renesas/ravb_main.c | 36 ++++++++++++++++++------
>   2 files changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
> index e5ca12ce93c730a9..7453b17a37a2c8d0 100644
> --- a/drivers/net/ethernet/renesas/ravb.h
> +++ b/drivers/net/ethernet/renesas/ravb.h
> @@ -1038,6 +1038,7 @@ struct ravb_private {
>   	unsigned wol_enabled:1;
>   	unsigned rxcidm:1;		/* RX Clock Internal Delay Mode */
>   	unsigned txcidm:1;		/* TX Clock Internal Delay Mode */
> +	unsigned rgmii_override:1;	/* Deprecated rgmii-*id behavior */
>   	int num_tx_desc;		/* TX descriptors per packet */
>   };
>   
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index 59dadd971345e0d1..aa120e3f1e4d4da5 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1034,11 +1034,8 @@ static int ravb_phy_init(struct net_device *ndev)
>   		pn = of_node_get(np);
>   	}
>   
> -	iface = priv->phy_interface;
> -	if (priv->chip_id != RCAR_GEN2 && phy_interface_mode_is_rgmii(iface)) {
> -		/* ravb_set_delay_mode() takes care of internal delay mode */
> -		iface = PHY_INTERFACE_MODE_RGMII;
> -	}
> +	iface = priv->rgmii_override ? PHY_INTERFACE_MODE_RGMII
> +				     : priv->phy_interface;
>   	phydev = of_phy_connect(ndev, pn, ravb_adjust_link, 0, iface);
>   	of_node_put(pn);
>   	if (!phydev) {
> @@ -1989,20 +1986,41 @@ static const struct soc_device_attribute ravb_delay_mode_quirk_match[] = {
>   };
>   
>   /* Set tx and rx clock internal delay modes */
> -static void ravb_parse_delay_mode(struct net_device *ndev)
> +static void ravb_parse_delay_mode(struct device_node *np, struct net_device *ndev)
>   {
>   	struct ravb_private *priv = netdev_priv(ndev);
> +	bool explicit_delay = false;
> +	u32 delay;
> +
> +	if (!of_property_read_u32(np, "rx-internal-delay-ps", &delay)) {
> +		/* Valid values are 0 and 1800, according to DT bindings */
> +		priv->rxcidm = !!delay;
> +		explicit_delay = true;
> +	}
> +	if (!of_property_read_u32(np, "tx-internal-delay-ps", &delay)) {
> +		/* Valid values are 0 and 2000, according to DT bindings */
> +		priv->txcidm = !!delay;
> +		explicit_delay = true;
> +	}
There are helper functions for this

s32 phy_get_internal_delay(struct phy_device *phydev, struct device 
*dev, const int *delay_values, int size, bool is_rx)