netdev - Re: [PATCH 1/2] net: phy: at803x: Fix RGMII RX and TX clock delays setup

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Date:   Wed, 19 Jul 2017 15:11:43 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Marc Gonzalez <marc_gonzalez@...madesigns.com>,
        Andrew Lunn <andrew@...n.ch>, Mans Rullgard <mans@...sr.com>,
        Martin Blumenstingl <martin.blumenstingl@...il.com>,
        Fabio Estevam <fabio.estevam@....com>,
        Zefir Kurtisi <zefir.kurtisi@...atec.com>,
        Timur Tabi <timur@...eaurora.org>,
        Daniel Mack <zonque@...il.com>, Sekhar Nori <nsekhar@...com>
CC:     netdev <netdev@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "David S. Miller" <davem@...emloft.net>,
        Thibaud Cornic <thibaud_cornic@...madesigns.com>,
        Mason <slash.tmp@...e.fr>
Subject: Re: [PATCH 1/2] net: phy: at803x: Fix RGMII RX and TX clock delays
 setup



On 07/19/2017 02:30 PM, Florian Fainelli wrote:
> On 07/19/2017 12:24 PM, Grygorii Strashko wrote:
>> Hi
>>
>> On 07/19/2017 10:31 AM, Marc Gonzalez wrote:
>>> The current code supports enabling RGMII RX and TX clock delays.
>>> The unstated assumption is that these settings are disabled by
>>> default at reset, which is not the case.
>>>
>>> RX clock delay is enabled at reset. And TX clock delay "survives"
>>> across SW resets. Thus, if the bootloader enables TX clock delay,
>>> it will remain enabled at reset in Linux.
>>>
>>> Provide disable functions to configure the RGMII clock delays
>>> exactly as specified in the fwspec.
>>>
>>> Signed-off-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>
>>> ---
>>>    drivers/net/phy/at803x.c | 32 ++++++++++++++++++++++++--------
>>>    1 file changed, 24 insertions(+), 8 deletions(-)
>> This patch breaks am335x-evm networking.
>>
>> To restore it I've had to apply below diff:
>> diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts
>> index 200d6ab..9578bdf 100644
>> --- a/arch/arm/boot/dts/am335x-evm.dts
>> +++ b/arch/arm/boot/dts/am335x-evm.dts
>> @@ -724,12 +724,12 @@
>>   
>>   &cpsw_emac0 {
>>          phy_id = <&davinci_mdio>, <0>;
>> -       phy-mode = "rgmii-txid";
>> +       phy-mode = "rgmii-id";
>>   };
>>   
>>   &cpsw_emac1 {
>>          phy_id = <&davinci_mdio>, <1>;
>> -       phy-mode = "rgmii-txid";
>> +       phy-mode = "rgmii-id";
>>   };
>>   
>>   &tscadc {
>>
>> Sry, can't comment here to much - not E-PHY expert.
> 
> It's useful feedback, since we had poorly defined "phy-mode" semantics
> for too long, this is totally expected, Marc this is exactly why Mans is
> suggesting additional MAC-specific properties to define delays.
> 

Yeah. original commit is pretty old and description is not very useful

commit 6d75afe2916adf9e9de6862275cdf89b9b7e4d0e
Author: Mugunthan V N <mugunthanvnm@...com>
Date:   Mon Jun 3 20:10:11 2013 +0000

     ARM: dts: AM33XX: Add phy-mode to CPSW node


-- 
regards,
-grygorii