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From: Piergiorgio Beruto <Pier.Beruto@onsemi.com>
To: Andrew Lunn <andrew@lunn.ch>
CC: Selvamani Rajagopal <Selvamani.Rajagopal@onsemi.com>,
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	<Nicolas.Ferre@microchip.com>,
        "benjamin.bigler@bernformulastudent.ch"
	<benjamin.bigler@bernformulastudent.ch>,
        Viliam Vozar
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        Arndt Schuebel <Arndt.Schuebel@onsemi.com>
Subject: RE: [PATCH net-next v4 00/12] Add support for OPEN Alliance
 10BASE-T1x MACPHY Serial Interface
Thread-Topic: [PATCH net-next v4 00/12] Add support for OPEN Alliance
 10BASE-T1x MACPHY Serial Interface
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Date: Thu, 30 May 2024 09:43:56 +0000
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Hello Andrew,

I was reading back into the MACPHY specifications in OPEN Alliance, and it =
seems like MMS 10 to MMS 15 are actually allowed as vendor specific registe=
rs. See page 50.
The specifications further say that vendor specific registers of the PHY th=
at would normally be in MMD30-31 (ie, excluding the PLCA registers and the =
other OPEN standard registers) would go into MMS10 to MMS15.

So I'm wondering, why is it bad to have vendor specific registers into MMD1=
0 to MMD15?
I think the framework should allow non-standard stuff to be mapped into the=
se, no?

Thanks,
Piergiorgio

-----Original Message-----
From: Andrew Lunn <andrew@lunn.ch>=20
Sent: 24 May, 2024 23:55
To: Piergiorgio Beruto <Pier.Beruto@onsemi.com>
Cc: Selvamani Rajagopal <Selvamani.Rajagopal@onsemi.com>; Parthiban.Veeraso=
oran@microchip.com; davem@davemloft.net; edumazet@google.com; kuba@kernel.o=
rg; pabeni@redhat.com; horms@kernel.org; saeedm@nvidia.com; anthony.l.nguye=
n@intel.com; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; corbet@l=
wn.net; linux-doc@vger.kernel.org; robh+dt@kernel.org; krzysztof.kozlowski+=
dt@linaro.org; conor+dt@kernel.org; devicetree@vger.kernel.org; Horatiu.Vul=
tur@microchip.com; ruanjinjie@huawei.com; Steen.Hegelund@microchip.com; vla=
dimir.oltean@nxp.com; UNGLinuxDriver@microchip.com; Thorsten.Kummermehr@mic=
rochip.com; Nicolas.Ferre@microchip.com; benjamin.bigler@bernformulastudent=
ch
Subject: Re: [PATCH net-next v4 00/12] Add support for OPEN Alliance 10BASE=
-T1x MACPHY Serial Interface

[External Email]: This email arrived from an external source - Please exerc=
ise caution when opening any attachments or clicking on links.

> In reality, it is not the PHY having register in MMS12, and not even=20
> the MAC. These are really "chip-specific" registers, unrelated to=20
> networking (e.g., GPIOs, HW diagnostics, etc.).

Having a GPIO driver within the MAC driver is O.K. For hardware diagnostics=
 you should be using devlink, which many MAC drivers have. So i don't see a=
 need for the PHY driver to access MMS 12.

Anyway, we can do a real review when you post your code.

> Although, I think it is a good idea anyway to allow the MACPHY drivers=20
> to hook into / extend the MDIO access functions.  If anything, because=20
> of the hacks you mentioned. But also to allow vendor-specific=20
> extensions.

But we don't want vendor specific extensions. OS 101, the OS is there to ma=
ke all hardware look the same. And in general, it is not often that vendors=
 actually come up with anything unique. And if they do, and it is useful, o=
ther vendors will copy it. So rather than doing vendor specific extensions,=
 you should be thinking about how to export it in a way which is common acr=
oss multiple vendors.

   Andrew