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From: Madalin Bucur <madalin.bucur@nxp.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "Russell King" <linux@armlinux.org.uk>,
	"Pali Rohár" <pali@kernel.org>,
	"Igal Liberman" <Igal.Liberman@freescale.com>,
	"Shruti Kanetkar" <Shruti@freescale.com>,
	"Emil Medve" <Emilian.Medve@freescale.com>,
	"Scott Wood" <oss@buserror.net>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Camelia Alexandra Groza (OSS)" <camelia.groza@oss.nxp.com>
Subject: RE: Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts
Date: Fri, 4 Jun 2021 21:47:26 +0000	[thread overview]
Message-ID: <AM6PR04MB39760B986E86BA9169DEECC5EC3B9@AM6PR04MB3976.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <YLqLzOltcb6jan+B@lunn.ch>

> -----Original Message-----
> From: Andrew Lunn <andrew@lunn.ch>
> Sent: 04 June 2021 23:24
> To: Madalin Bucur <madalin.bucur@nxp.com>
> Cc: Russell King <linux@armlinux.org.uk>; Pali Rohár <pali@kernel.org>;
> Igal Liberman <Igal.Liberman@freescale.com>; Shruti Kanetkar
> <Shruti@freescale.com>; Emil Medve <Emilian.Medve@freescale.com>; Scott
> Wood <oss@buserror.net>; Rob Herring <robh+dt@kernel.org>; Michael
> Ellerman <mpe@ellerman.id.au>; Benjamin Herrenschmidt
> <benh@kernel.crashing.org>; netdev@vger.kernel.org;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Camelia
> Alexandra Groza (OSS) <camelia.groza@oss.nxp.com>
> Subject: Re: Unsupported phy-connection-type sgmii-2500 in
> arch/powerpc/boot/dts/fsl/t1023rdb.dts
> 
> > The "sgmii-2500" compatible in that device tree describes an SGMII HW
> > block, overclocked at 2.5G. Without that overclocking, it's a plain
> > Cisco (like) SGMII HW block. That's the reason you need to disable it's
> > AN setting when overclocked. With the proper Reset Configuration Word,
> > you could remove the overclocking and transform that into a plain
> "sgmii".
> > Thus, the dts compatible describes the HW, as it is.
> 
> It sounds like the hardware is capable of swapping between SGMII and
> 2500BaseX.
> 
> What we have in DT in this case is not describing the hardware, but
> how we configure the hardware. It is one of the few places we abuse DT
> for configuration.
> 
>     Andrew

The actual selection of this mode of operation is performed by the so called
Reset Configuration Word from the boot media, that aligned with the HW and
board design. The need to name it something other than plain "sgmii" comes
from the HW special need for AN to be disabled to operate.

Actually, the weird/non-standard hardware is described by the device tree
with a value that puts it in a class of its own. Instead of the overclocked
SGMII denomination "sgmii-2500" it could have been named just as well
"overclocked-nonstandard-2.5G-ethernet-no-autoneg-SGMII-hw-ip".

One could try to change device trees to slip configuration details, but the
backwards compatibility aspect renders this futile. Is there any option to
say "sgmii" then "autoneg disabled"?

Madalin

  reply	other threads:[~2021-06-04 21:47 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-03 14:34 Pali Rohár
2021-06-03 15:12 ` Andrew Lunn
2021-06-03 19:48   ` Pali Rohár
2021-06-04  7:35     ` Madalin Bucur
2021-06-04 17:32       ` Pali Rohár
2021-06-04 19:13         ` Madalin Bucur
2021-06-04 19:27       ` Russell King (Oracle)
2021-06-04 19:39         ` Madalin Bucur
2021-06-04 20:00           ` Russell King (Oracle)
2021-06-04 21:37             ` Madalin Bucur
2021-06-04 20:23           ` Andrew Lunn
2021-06-04 21:47             ` Madalin Bucur [this message]
2021-06-04 23:34               ` Pali Rohár
2021-06-05  0:33                 ` Russell King (Oracle)
2021-06-05 12:26                   ` Vladimir Oltean
2021-06-05 12:50                     ` What is inside GPON SFP module? (Was: Re: Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts) Pali Rohár
2021-06-05 13:04                       ` Hauke Mehrtens
2021-06-05 13:31                         ` What is inside GPON SFP module? Pali Rohár
2021-06-05 14:17                           ` Hauke Mehrtens
2021-06-05 14:41                         ` What is inside GPON SFP module? (Was: Re: Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts) Russell King (Oracle)
2021-06-08 10:33                           ` What is inside GPON SFP module? Pali Rohár
2021-06-19 20:35                 ` Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts Pali Rohár
2021-07-04 13:43                 ` [PATCH] powerpc/fsl/dts: Fix phy-connection-type for fm1mac3 Pali Rohár
2021-07-14 17:11                   ` Scott Wood
2021-08-27 11:38                     ` Pali Rohár
2021-09-28 21:39                       ` Pali Rohár
2021-09-29 14:25                         ` Andrew Lunn
2021-10-02  9:06                           ` Pali Rohár
2021-06-04 23:18         ` Unsupported phy-connection-type sgmii-2500 in arch/powerpc/boot/dts/fsl/t1023rdb.dts Pali Rohár

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