netdev - Re: [PATCH/RFC 3/5] ravb: Add support for explicit internal clock delay configuration

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Message-ID: <6935aea3-0acd-f1b9-b36c-553b8c3106d1@cogentembedded.com>
Date:   Sat, 20 Jun 2020 22:03:29 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Geert Uytterhoeven <geert+renesas@...der.be>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH/RFC 3/5] ravb: Add support for explicit internal clock
 delay configuration

On 06/19/2020 10:15 PM, 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 "renesas,[rt]xc-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>

> ---
>  drivers/net/ethernet/renesas/ravb.h      |  1 +
>  drivers/net/ethernet/renesas/ravb_main.c | 35 ++++++++++++++++++------
>  2 files changed, 27 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 f326234d1940f43e..0582846bec7726b6 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
[...]
> @@ -1967,20 +1963,41 @@ 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, "renesas,rxc-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, "renesas,txc-delay-ps", &delay)) {
> +		/* Valid values are 0 and 2000, according to DT bindings */
> +		priv->txcidm = !!delay;
> +		explicit_delay = true;
> +	}
>  
> +	if (explicit_delay)
> +		return;
> +
> +	/* Fall back to legacy rgmii-*id behavior */
>  	if (priv->phy_interface == PHY_INTERFACE_MODE_RGMII_ID ||
> -	    priv->phy_interface == PHY_INTERFACE_MODE_RGMII_RXID)
> +	    priv->phy_interface == PHY_INTERFACE_MODE_RGMII_RXID) {
>  		priv->rxcidm = true;
> +		priv->rgmii_override = true;

   Mhm, these fields are not bool...

> +	}
>  
>  	if (priv->phy_interface == PHY_INTERFACE_MODE_RGMII_ID ||
>  	    priv->phy_interface == PHY_INTERFACE_MODE_RGMII_TXID) {
>  		if (!WARN(soc_device_match(ravb_delay_mode_quirk_match),
>  			  "phy-mode %s requires TX clock internal delay mode which is not supported by this hardware revision. Please update device tree",
> -			  phy_modes(priv->phy_interface)))
> +			  phy_modes(priv->phy_interface))) {
>  			priv->txcidm = true;
> +			priv->rgmii_override = true;

    Same here...

[...]

MBR, Sergei