linux-kernel - Re: [PATCH v2 1/2] net: phy: realtek: Add rtl8211e rx/tx delays config

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Date:   Fri, 26 Apr 2019 20:11:50 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Serge Semin <fancer.lancer@...il.com>, Andrew Lunn <andrew@...n.ch>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Serge Semin <Sergey.Semin@...latforms.ru>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] net: phy: realtek: Add rtl8211e rx/tx delays
 config



On 4/26/2019 4:45 PM, Serge Semin wrote:
> On Fri, Apr 26, 2019 at 11:40:50PM +0200, Andrew Lunn wrote:
>> On Sat, Apr 27, 2019 at 12:21:11AM +0300, Serge Semin wrote:
>>> There are two chip pins named TXDLY and RXDLY which actually adds the 2ns
>>> delays to TXC and RXC for TXD/RXD latching. Alas this is the only
>>> documented info regarding the RGMII timing control configurations the PHY
>>> provides. It turns out the same settings can be setup via MDIO registers
>>> hidden in the extension pages layout. Particularly the extension page 0xa4
>>> provides a register 0x1c, which bits 1 and 2 control the described delays.
>>> They are used to implement the "rgmii-{id,rxid,txid}" phy-mode.
>>>
>>> The hidden RGMII configs register utilization was found in the rtl8211e
>>> U-boot driver:
>>> https://elixir.bootlin.com/u-boot/v2019.01/source/drivers/net/phy/realtek.c#L99
>>>
>>> There is also a freebsd-folks discussion regarding this register:
>>> https://reviews.freebsd.org/D13591
>>>
>>> It confirms that the register bits field must control the so called
>>> configuration pins described in the table 12-13 of the official PHY
>>> datasheet:
>>> 8:6 = PHY Address
>>> 5:4 = Auto-Negotiation
>>> 3 = Interface Mode Select
>>> 2 = RX Delay
>>> 1 = TX Delay
>>> 0 = SELRGV
>>>
>>> Signed-off-by: Serge Semin <fancer.lancer@...il.com>
>>
>>
>> Hi Serge
>>
>> Next time please include a patch 0 containing a cover note explaining
>> the who series.
>>
> 
> Sure as long as the patchset gets to be much bigger than two small
> patches with an obvious reason to be merged.

netdev likes to have a cover letter for patch count >= 1, probably
something to be added to netdev-FAQ.rst.
-- 
Florian