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

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Message-ID: <abbcd40c-5ecd-2197-73d0-2046cf1e7b5c@gmail.com>
Date:   Wed, 19 Jul 2017 12:30:24 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Grygorii Strashko <grygorii.strashko@...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 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.
-- 
Florian