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

Open Source and information security mailing list archives

Date:   Thu, 24 Aug 2017 16:05:54 +0800
From:   icenowy@...c.io
To:     Andrew Lunn <andrew@...n.ch>
Cc:     devicetree@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>,
        netdev@...r.kernel.org, linux-sunxi@...glegroups.com,
        linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>,
        Corentin Labbe <clabbe.montjoie@...il.com>,
        Icenowy Zheng <icenowy@...c.xyz>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 3/4] net: phy: realtek: add disable RX internal delay
 mode

在 2017-08-22 21:39，Andrew Lunn 写道：
> 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.

In fact I'm not sure -- I'm even not sure that after making this change
there's no TX delay. The change is totally not documented, so I choose
to use a custom property in v1.

But Florian required me to use RGMII-TXID instead.

> 
>> +#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
> 
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