linux-kernel - Re: [PATCH] ARM: dts: add phy-reset property for rk3066a-rayeager emac

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Date:   Thu, 9 Nov 2017 10:40:03 +0200
From:   Roger Quadros <rogerq@...com>
To:     Chris Zhong <zyw@...k-chips.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        <andrew@...n.ch>
CC:     Mark Rutland <mark.rutland@....com>, <devicetree@...r.kernel.org>,
        <heiko@...ech.de>, <netdev@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>,
        <linux-kernel@...r.kernel.org>,
        <linux-rockchip@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: dts: add phy-reset property for rk3066a-rayeager
 emac

On 09/11/17 10:28, Roger Quadros wrote:
> On 08/11/17 11:49, Chris Zhong wrote:
>> Hi Florian Fainelli
>>
>>
>> On 2017年11月08日 02:26, Florian Fainelli wrote:
>>> On 11/07/2017 01:51 AM, Chris Zhong wrote:
>>>>
>>>> On 2017年11月07日 15:54, Vladimir Zapolskiy wrote:
>>>>> Hello Chris,
>>>>>
>>>>> On 11/07/2017 04:49 AM, Chris Zhong wrote:
>>>>>> The ethernet phy of rk3066a-rayeager has a reset pin, it controlled by
>>>>>> GPIO1_D6, this pin should be pull down then pull up to reset the phy.
>>>>>> Add a phy-reset property in emac, make the phy can be reset when emac
>>>>>> power on.
>>>>> for PHY reset there are properties 'reset-gpios' and 'reset-delay-us',
>>>>> please reference to Documentation/devicetree/bindings/net/mdio.txt
>>>>>
>>>>> Can you try to reuse them instead of adding new custom properties?
>>>> This phy-reset is from Documentation/devicetree/bindings/net/arc_emac.txt.
>>>> And copy from arch/arm/boot/dts/rk3036-kylin.dts.
>>>> Can we just use these properties, they are not new.
>>> Because it already exists does not mean it's correct, in fact, it is not
>>> at all because it places the reset property for a PHY into the MAC node,
>>> which is just not what this is, what we should be using instead is the
>>> following patch series:
>>>
>>> http://patchwork.ozlabs.org/project/netdev/list/?series=9267
>>>
>>> http://patchwork.ozlabs.org/patch/828499/
>>> http://patchwork.ozlabs.org/patch/828505/
>>> http://patchwork.ozlabs.org/patch/828501/
>>> http://patchwork.ozlabs.org/patch/828502/
>> Okay, this series works for me, and I will push a new version patch following it,
>> with a reset-gpios property under phy node.
>> And hope this series can be applied soon.
>>
> 
> If 'reset-gpios' and 'reset-delay-us' as per [1] works for you
> then why not use that?
> 
> [1] Documentation/devicetree/bindings/net/mdio.txt

I take back my statement.

You should use the above only if you have a single reset line connected to multiple PHYs
on the same MDIO bus.
In all other cases the reset properties should be part of PHY device node.

However, we need to still ensure that the mdio_bus driver issues the reset. This piece
is still missing in the code.

> 
>> Thanks
>> Chris Zhong
>>
>>
>>>>> As a side question, which is mainly addressed to Sergei and Roger,
>>>>> I don't quite understand why PHY properties were initially added to
>>>>> MAC/MDIO bus device tree nodes, in my opinion they must be moved under
>>>>> PHY device tree nodes.
>>>>>
>>>>> -- 
>>>>> With best wishes,
>>>>> Vladimir
>>>>>
>>>>>> Signed-off-by: Chris Zhong <zyw@...k-chips.com>
>>>>>> ---
>>>>>>
>>>>>>    arch/arm/boot/dts/rk3066a-rayeager.dts | 2 ++
>>>>>>    1 file changed, 2 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>>>> b/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>>>> index 570157f..6064a0a 100644
>>>>>> --- a/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>>>> +++ b/arch/arm/boot/dts/rk3066a-rayeager.dts
>>>>>> @@ -173,6 +173,8 @@
>>>>>>        pinctrl-0 = <&emac_xfer>, <&emac_mdio>, <&rmii_rst>;
>>>>>>        phy = <&phy0>;
>>>>>>        phy-supply = <&vcc_rmii>;
>>>>>> +    phy-reset-gpios = <&gpio1 RK_PD6 GPIO_ACTIVE_LOW>; /* PHY_RST */
>>>>>> +    phy-reset-duration = <10>; /* millisecond */
>>>>>>        status = "okay";
>>>>>>          phy0: ethernet-phy@0 {
>>>>>>
>>>>>
>>>
>>
> 

-- 
cheers,
-roger

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