LS1046ARDB board SFP+ module not working with 1G SFP tranceiver

[gkrishna]

Hi,

I am testing the SFP+ port with 1G Modules since it does have backward compatability but I am unable to make it work in LS1056ARDB.

Does it work? or do we need to modify any RCW values, if we need to modify then please let me know the information.

[yipingwang]

If configuring SERDES lane as SGMII mode, a SGMII PHY is required on the target board. If configuring it as XFI, a 10G SFP+ module is required. 

1G SFP is not supported.

[gkrishna]

Hi,

Our custom board based on ls1046a serdes directly connected to SFP cage and serdes is configured as SGMII, our HW designer says that this connection directly should work without phy or XFI with 1G SFP, even though auto link may not work, but manually setting the link should work. We are in design state and we would like to confirm with you people. Could you please confirm?

[yipingwang]

In order to use 1G SFP, you need to use backplane driver, the serdes needs to be configured as 1000base-x

Please refer to the attachment for the spec which FMAN supports.

[vladimir_oltean]

> In order to use 1G SFP, you need to use backplane driver, the serdes needs to be configured as 1000base-x

This is not correct, you do not need to use the backplane driver (described here https://docs.nxp.com/bundle/UG10143/page/AN14142_topics/AN14142_overview.html) for 1G SFP modules. The 1G link mode which is negotiated using clause 73 over copper backplanes is called 1000Base-KX, notice the K (bacKplane).

Whereas SFP modules typically use 1000Base-SX (short range fiber optics), 1000Base-LX (long range fiber optics) or SGMII (modules with PHY inside, for conversion to RJ45). The selection among these operating modes is done by phylink once it is determined which module was inserted, by reading the EEPROM. At the PCS layer, 1000Base-SX and 1000Base-LX are the same and are simply called 1000Base-X. The same PCS handles 1000Base-X and SGMII, there is just one setting denoting whether to use SGMII format for auto-negotiation (with PHYs inside RJ45 SFP modules, or with on-board PHYs) or the 1000Base-X format (with the link partner from the remote end of the fiber).

The only requirement which has to be fulfilled by the device driver is to use the phylink framework. DPAA1 has 2 Ethernet driver variants as explained here: https://docs.nxp.com/bundle/UG10143/page/topics/introduction_019.html

The "private"/"SDK" version of the DPAA1 Ethernet driver does not use phylink, thus it does not support the CONFIG_SFP framework and cannot reconfigure in response to the insertion of SFP modules.

The "upstream" version of the DPAA1 Ethernet driver, also distributed with Linux Factory, supports this capability. But it is further limited by board support.

[gkrishna]

Thank you for the info, Could you please let me know how the backplane driver can be built? whether its a part of u-boot? and do we need to changes anyting in the driver to make it work other than serdes configuration in RCW? please let us know.

[yipingwang]

The latest Backplane Linux Kernel 6.1 is provided in tag BACKPLANE-V6.1-R2.0(https://github.com/nxp-qoriq/linux-extras/releases/tag/BACKPLANE-V6.1-R2.0)

You could clone the source code with the following commands.

$ git clone https://github.com/git/nxp-qoriq/linux

$ git checkout -b BACKPLANE-V6.1-R2.0 BACKPLANE-V6.1-R2.0

[gkrishna]

Hi,

Thank you for the source, one final thing is whether it can be tested through u-boot cli apart from kernel back plane driver?

Please let me know, because in the bring up stage we will we be having only u-boot, We would like to make sure.

[yipingwang]

No backplane driver for u-boot.

Please refer to 

https://www.nxp.com.cn/docs/en/application-note/AN12572.pdf

[gkrishna]

Hi Yipingwang,

I got your info, we have got the custom board in bring up, I would not need auto negotiation still do I need backplane drive for this setup which I explained because I got to know the backplane driver needed incase of autonegotiation. Please confirm and also your document described about 10G not 1G.

If there is any similar dts available in the already got repo, please point it.

As of now we enabled RCW serdes as sgmii interface and the necessary clock like 1.25M.

Then in the dts, physical connection as sgmii and fixed link with 1000.

The interface seems up, I got that the TX bytes increase even in ethtool but I don't see any packets really coming out of that. Fixed speed link is enough for us, pls confirm still backplane driver needed or not and also the dts changes if required.

Thanks,

Gopi Krishna M

[gkrishna]

Hi,

Thanks for your comments, In our custom board based on ls1046ardb, we take SERDES1 SGMII directly to SFP Cage(without XRET Timer) where we support only 1G(NO 10G), SFP interfcae, In that case, SERDES shoud be defined as SGMII in RCW and then it shoud work right? or do we need to do anything else? please clarify.

[yipingwang]

1. If configuring SERDES 1 lane C as SGMII mode, a SGMII PHY is required on the target board. If configuring it as XFI, a 10G SFP+ module is required. It seems that this doesn't meet the requirement of your product to configure the Ethernet interface to support both 1G and 10 G, because you only can choose SERDES 1 lane C in one mode.

2. One common Optic SFP+ that does do both 1G and 10G, such as Intel E10GSFPSR and Intel E10GSFPLR, maybe you need to contact Intel for detailed information of these products.

3. XFI is always 10G. If you need speed switching and can use a PHY, for example choosing Aquantia (NBASE-T Alliance) or Broadcom (MGBASE-T Alliance). On LS1046ARDB, XFI 9 working with Aquantia AQR107 supports 10G/5G/2.5G/1G/100M.