linux-kernel - Re: [PATCH v2 3/4] net: phy: realtek: add disable RX internal delay mode

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Message-ID: <20170822133906.GG24555@lunn.ch>
Date:   Tue, 22 Aug 2017 15:39:06 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Icenowy Zheng <icenowy@...c.io>
Cc:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Corentin Labbe <clabbe.montjoie@...il.com>,
        devicetree@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com,
        Icenowy Zheng <icenowy@...c.xyz>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 3/4] net: phy: realtek: add disable RX internal delay
 mode

On Tue, Aug 22, 2017 at 12:03:59PM +0800, Icenowy Zheng wrote:
> From: Icenowy Zheng <icenowy@...c.xyz>
> 
> Some RTL8211E chips have broken GbE function, which needs a hack to
> fix. It's said that this fix will affect the performance on not-buggy
> PHYs, so it should only be enabled on boards with the broken PHY.

I would not call this a broken PHY. It is a question of board
design. If you have shorter tracks, you need a delay. If you have long
tracks, you don't. Hence the four RGMII modes, so you can select if
the delay is needed or not, depending on your board design.

> Currently only some Pine64+ boards are known to have this issue.

Design feature.

Please remove all reference to bug.

> This hack is said to disable RX relay for RTL8211E according to Realtek.
> So implement it as RGMII-TXID mode.

Do we know that the TX lines do have a delay after making this change?
We need to be careful here. We will get into a mess if this is
actually RGMII not RGMII_TXID, and somebody designs a board which
needs RGMII-TXID.

> +#include <linux/of.h>
>  #include <linux/phy.h>
>  #include <linux/module.h>

> +static int rtl8211e_config_init(struct phy_device *phydev)
> +{
> +	struct device *dev = &phydev->mdio.dev;
> +	struct device_node *of_node = dev->of_node;

You don't appear to use of_node, nor dev. Please remove, along with
the header file.

    Andrew