RE: [PATCH 1/3][v2] net: phy: introduce 1000BASE-KX and 10GBASE-KR

quoted

If you look at the list of possible values for "phy-mode" you'd see
that none of it describes a PHY-to-PHY connection but all are for
MAC-to-PHY connections. Also, names above suggest it already: MII is
short for media _independent_ interface.

I copy Andrew's concerns and think that neither 10000base-kx nor
10gbase-kr belong in the list of phy-mode properties.

I concur with that as well, if the phy connection does not really matter here,
or does not seem like a good fit, maybe we should have a different property, or
just define the hardware interface a little differently?

Right, 'phy-mode' is not a good fit for backplanes, how about a new property like
'backplane-mode' or something, like below:

--- a/Documentation/devicetree/bindings/net/phy.txt
+++ b/Documentation/devicetree/bindings/net/phy.txt

@@ -33,6 +33,9 @@ Optional Properties:
 - broken-turn-around: If set, indicates the PHY device does not correctly
   release the turn around line low at the end of a MDIO transaction.
 
+- backplane-mode: string, operation mode of the backplane PHY;
+  must be "1000base-kx" for 1000BASE-KX, or "10gbase-kr" for 10GBASE-KR.
+
 Example:
 
 ethernet-phy@0 {

Thank you!

Shaohui
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On 18.01.2016 08:23, Shaohui Xie wrote:

quoted

quoted

If you look at the list of possible values for "phy-mode" you'd see
that none of it describes a PHY-to-PHY connection but all are for
MAC-to-PHY connections. Also, names above suggest it already: MII is
short for media _independent_ interface.

I copy Andrew's concerns and think that neither 10000base-kx nor
10gbase-kr belong in the list of phy-mode properties.

I concur with that as well, if the phy connection does not really matter here,
or does not seem like a good fit, maybe we should have a different property, or
just define the hardware interface a little differently?

Right, 'phy-mode' is not a good fit for backplanes, how about a new property like
'backplane-mode' or something, like below:

Hmm. We already have a speed property for that you can use for
1000, 10000, 40000. Leaves the media-type, e.g. copper or whatever.

Currently, you fail to convince me that it is required to describe
the media type at all. We have come a long way with different media
without describing the PHY-to-PHY media type.

What makes the backplane setup so special?

Sebastian

-----Original Message-----
From: Sebastian Hesselbarth [mailto:sebastian.hesselbarth@gmail.com]
Sent: Monday, January 18, 2016 4:06 PM
To: Shaohui Xie; Florian Fainelli; Andrew Lunn; shh.xie@gmail.com
Cc: devicetree@vger.kernel.org; netdev@vger.kernel.org; linuxppc-
dev@lists.ozlabs.org; davem@davemloft.net; Shaohui Xie
Subject: Re: [PATCH 1/3][v2] net: phy: introduce 1000BASE-KX and 10GBASE-KR

On 18.01.2016 08:23, Shaohui Xie wrote:

quoted

quoted

quoted

If you look at the list of possible values for "phy-mode" you'd see
that none of it describes a PHY-to-PHY connection but all are for
MAC-to-PHY connections. Also, names above suggest it already: MII is
short for media _independent_ interface.

I copy Andrew's concerns and think that neither 10000base-kx nor
10gbase-kr belong in the list of phy-mode properties.

I concur with that as well, if the phy connection does not really
matter here, or does not seem like a good fit, maybe we should have a
different property, or just define the hardware interface a little

differently?

quoted

Right, 'phy-mode' is not a good fit for backplanes, how about a new
property like 'backplane-mode' or something, like below:

Hmm. We already have a speed property for that you can use for 1000, 10000,
40000. Leaves the media-type, e.g. copper or whatever.

[S.H] You mean the property 'max-speed'? the problem is the media-type matters.
Please see below.

Currently, you fail to convince me that it is required to describe the media
type at all. We have come a long way with different media without describing the
PHY-to-PHY media type.

What makes the backplane setup so special?

[S.H] the fsl backplane, e.g. 10GBASE-KR, needs software to handle link training,
It's to train link partner, and trained by link partner parallel.

But if media type is not copper, e.g. optical module, we won't need this.

Thank you!

Shaohui