netdev - Re: [PATCH 0/3] net: phy: initialize PHYs via device tree properties

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Date:   Tue, 29 Oct 2019 21:54:53 +0100
From:   Michael Walle <michael@...le.cc>
To:     Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        netdev@...r.kernel.org
CC:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 0/3] net: phy: initialize PHYs via device tree properties

Am 29. Oktober 2019 18:59:07 MEZ schrieb Florian Fainelli <f.fainelli@...il.com>:
>On 10/29/19 10:48 AM, Michael Walle wrote:
>> I was trying to configure the Atheros PHY for my board. There are
>fixups
>> all over the place, for example to enable the 125MHz clock output in
>almost
>> any i.MX architecture. Instead of adding another fixup in
>architecture
>> specific code, try to provide a generic way to init the PHY
>registers.
>> 
>> This patch series tries to pick up the "broadcom,reg-init" and
>> "marvell,reg-init" device tree properties idea and make it a more
>generic
>> "reg-init" which is handled by phy_device instead of a particular phy
>> driver.
>
>These two examples are actually quite bad and were symptomatic of a few
>things at the time:
>
>- rush to get a specific feature/device supported without thinking
>about
>the big picture
>- lack of appropriate review on the Device Tree bindings
>
>Fortunately, the last item is now not happening anymore.
>
>The problem with letting that approach go through is that the Device
>Tree can now hold a configuration policy which is passed through as-is
>from DT to the PHY device, this is bad on so many different levels,
>starting with abstraction.

I see.

>If all you need is to enable a particular clock, introduce device
>specific properties that describe the hardware, and make the necessary
>change to the local driver that needs to act on those. You can always
>define a more generic scope property if you see a recurring pattern.

Could you have a quick look at the following patch I made for u-boot, which adds a binding for the Atheros PHY. If that is the right direction. Yeah, I should have made it first to Linux to get some feedback on the binding :p

https://patchwork.ozlabs.org/patch/1184516/

I'd then prepare another patch for Linux based on your suggestions. 

-michael 

>
>So just to be clear on the current approach: NACK.
>
>> 
>> Michael Walle (3):
>>   dt-bindings: net: phy: Add reg-init property
>>   net: phy: export __phy_{read|write}_page
>>   net: phy: Use device tree properties to initialize any PHYs
>> 
>>  .../devicetree/bindings/net/ethernet-phy.yaml | 31 ++++++
>>  MAINTAINERS                                   |  1 +
>>  drivers/net/phy/phy-core.c                    | 24 ++++-
>>  drivers/net/phy/phy_device.c                  | 97
>++++++++++++++++++-
>>  include/dt-bindings/net/phy.h                 | 18 ++++
>>  include/linux/phy.h                           |  2 +
>>  6 files changed, 170 insertions(+), 3 deletions(-)
>>  create mode 100644 include/dt-bindings/net/phy.h
>> 
>> Cc: Andrew Lunn <andrew@...n.ch>
>> Cc: Florian Fainelli <f.fainelli@...il.com>
>> Cc: Heiner Kallweit <hkallweit1@...il.com>
>> Cc: "David S. Miller" <davem@...emloft.net>
>> Cc: Rob Herring <robh+dt@...nel.org>
>> Cc: Mark Rutland <mark.rutland@....com>
>> 

Hi Florian,