On Saturday 05 June 2021 01:34:55 Pali Rohár wrote: > On Friday 04 June 2021 21:47:26 Madalin Bucur wrote: > > > -----Original Message----- > > > From: Andrew Lunn <andrew@xxxxxxx> > > > Sent: 04 June 2021 23:24 > > > To: Madalin Bucur <madalin.bucur@xxxxxxx> > > > Cc: Russell King <linux@xxxxxxxxxxxxxxx>; Pali Rohár <pali@xxxxxxxxxx>; > > > Igal Liberman <Igal.Liberman@xxxxxxxxxxxxx>; Shruti Kanetkar > > > <Shruti@xxxxxxxxxxxxx>; Emil Medve <Emilian.Medve@xxxxxxxxxxxxx>; Scott > > > Wood <oss@xxxxxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Michael > > > Ellerman <mpe@xxxxxxxxxxxxxx>; Benjamin Herrenschmidt > > > <benh@xxxxxxxxxxxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; > > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Camelia > > > Alexandra Groza (OSS) <camelia.groza@xxxxxxxxxxx> > > > 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 > > Madalin, my understanding is that "sgmii-2500" mode is unknown and > unsupported by kernel. > > List of known modes which can be specified in DTS file are defined in > YAML schema for 'phy-connection-type' in file: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/net/ethernet-controller.yaml?h=v5.12#n55 > > And there is none "sgmii-2500", so some DTS schema validator could throw > validation error for that DTS file. I'm not sure if somebody has written > DTS schema validator with all those things (like there are JSON schema > or OpenAPI validators in JavaScript / HTTP world). > > Plus also in linux/phy.h header file contains list of known Linux modes: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/phy.h?h=v5.12#n169 > > And based on all information in this email discussion, in my opinion the > mode which HW supports matches Linux meaning of "2500base-x" key/string. > So I would suggest to rename "sgmii-2500" in that DTS file to > "2500base-x". Does it make sense? Any opinion? Or should I send a patch?
