make menuconfig can't select MDIO_I2C (ksz9567 in 4.14 would be nice too)

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make menuconfig can't select MDIO_I2C (ksz9567 in 4.14 would be nice too)

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brian_hutchinso
Contributor II

On 4.14 kernel for imx8mm-evk, make menuconfig will not select CONFIG_MDIO_I2C.  Looks like some kind of bug around PHYLINK and some other Kconfig options that get set based on what is picked.  No matter what I do I can't get option turned on.  Looks like SFP (SFP cage support) has something to do with selecting MDIO_I2C but I can't get that to show up in make menuconfig to select.

I'd like to use the MDIO I2C bridge (drivers/net/phy/mdio-i2c.c)

because I have a custom board based on the imx8mm-evk and it uses a Microchip switch (ksz9567) that we wired up RGMII with I2C for management (no MDIO).  The linux driver that I need didn't get upstreamed until 5.x series kernel and there doesn't appear to be an imx8 supported kernel past 4.14 so it looks like I either have to cherry pick/back port a bunch (and I mean a bunch) of dsa stuff or find another option and since the switch is strapped to basically come up and run in PHY mode I thought using the generic PHY Linux driver and MDIO to I2C bridge might be a easy workaround for now ... if I could figure out how to get my .config to build it!

So I'm pulling my hair out and striking out every which way I turn trying to find a solution to get our Ethernet going on this new custom board.

Grateful for any ideas or suggestions,

Regards,

Brian

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Brian

regarding "make menuconfig can't select MDIO_I2C" - suggest to post

that on kernel mail list as this is not imx specific question

Majordomo Lists at VGER.KERNEL.ORG 

for switches may be useful to look at

i.MX6UL with KSZ8895 switch not working 

https://community.nxp.com/thread/463677 

Best regards
igor
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brian_hutchinso
Contributor II

Thanks,

I actually figured out the issue and now have MDIO_I2C set.  The issue is PHYLINK was never selected in any of the Kconfigs.  I compared the Kconfigs to 5.5 kernel and modified one of the 4.14 Kconfig files to select PHYLINK on one of the options just as it is done in the 5.5 kernel.  So now I have mdio-i2c being built.

… now trying to figure out how to use the bridge or if I even really need it.  I'm now thinking I can just use the generic phydev.

Regards,

Brian

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