netdev - Re: [PATCH 02/14] drivers: net: dsa: qca8k: tweak internal delay to oem spec

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Message-ID: <fdddeb1a-33c7-3087-86a1-f3b735a90eb1@gmail.com>
Date:   Thu, 22 Apr 2021 18:53:45 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/14] drivers: net: dsa: qca8k: tweak internal delay to
 oem spec



On 4/22/2021 6:47 PM, Ansuel Smith wrote:
> The original code had the internal dalay set to 1 for tx and 2 for rx.
> Apply the oem internal dalay to fix some switch communication error.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---
>  drivers/net/dsa/qca8k.c | 6 ++++--
>  drivers/net/dsa/qca8k.h | 9 ++++-----
>  2 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> index a6d35b825c0e..b8bfc7acf6f4 100644
> --- a/drivers/net/dsa/qca8k.c
> +++ b/drivers/net/dsa/qca8k.c
> @@ -849,8 +849,10 @@ qca8k_phylink_mac_config(struct dsa_switch *ds, int port, unsigned int mode,
>  		 */
>  		qca8k_write(priv, reg,
>  			    QCA8K_PORT_PAD_RGMII_EN |
> -			    QCA8K_PORT_PAD_RGMII_TX_DELAY(QCA8K_MAX_DELAY) |
> -			    QCA8K_PORT_PAD_RGMII_RX_DELAY(QCA8K_MAX_DELAY));
> +			    QCA8K_PORT_PAD_RGMII_TX_DELAY(1) |
> +			    QCA8K_PORT_PAD_RGMII_RX_DELAY(2) |
> +			    QCA8K_PORT_PAD_RGMII_TX_DELAY_EN |
> +			    QCA8K_PORT_PAD_RGMII_RX_DELAY_EN);

There are standard properties in order to configure a specific RX and TX
delay:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/net/ethernet-controller.yaml#n125

can you use that mechanism and parse that property, or if nothing else,
allow an user to override delays via device tree using these standard
properties?
-- 
Florian