AM3352: Linux - Activate MDIO driver with marvell switch 88E6341 (or other switch)

Avner Flesch

Part Number: AM3352

I have a board with Sitara AM3352 - the networking is not via Ethernet PHY, but with a switch (Marvell 88E6341) that is connected to the CPU with MII. the switch has a port that is connected to a PHY and RJ45 connector.

My Linux version is 4.14

I configured the dts file correctly for having a network, but I also want the MDIO driver to be active so I will be able to manage the switch.

It looks like I can interact the Sitara MDIO controller with "devmem" commands, but I prefer to do it the "normal" way with the kernel devinci-mdio driver.

My dts looks like this:

&cpsw_emac0 {

phy_id = <&davinci_mdio>, <0>;

fixed-link = <1 1 100 0 0>;

phy-mode = "mii";

};

&mac {

slaves = <1>;

pinctrl-names = "default", "sleep";

pinctrl-0 = <&cpsw_default>;

pinctrl-1 = <&cpsw_sleep>;

status = "okay";

};

&davinci_mdio {

compatible = "ti,cpsw-mdio";

pinctrl-names = "default", "sleep";

pinctrl-0 = <&davinci_mdio_default>;

pinctrl-1 = <&davinci_mdio_sleep>;

status = "okay";

};

This what I get in the dmesg:

[ 0.975182] mdio_bus fixed-0: GPIO lookup for consumer reset
[ 0.975195] mdio_bus fixed-0: using lookup tables for GPIO lookup
[ 0.975202] mdio_bus fixed-0: lookup for GPIO reset failed
[ 0.975223] libphy: Fixed MDIO Bus: probed
[ 0.994386] mdio_bus 4a101000.mdio: GPIO lookup for consumer reset
[ 0.994398] mdio_bus 4a101000.mdio: using lookup tables for GPIO lookup
[ 0.994405] mdio_bus 4a101000.mdio: lookup for GPIO reset failed
[ 1.047323] davinci_mdio 4a101000.mdio: davinci mdio revision 1.6, bus freq 1000000
[ 1.055025] davinci_mdio 4a101000.mdio: no live phy, scanning all
[ 1.061484] davinci_mdio 4a101000.mdio: mdiobus_register ret=-5

I think it is rather common such design - so if anybody managed to handle this issue, I will much appreciate it if he will share the knowledge.

Thanks

over 4 years ago

0 Schuyler Patton over 4 years ago

TI__Mastermind 40130 points

Hi,

Unfortunately TI does not able to support interfacing to an external switch. However, several users have successfully integrated an external switch on the CPSW of Sitara processors. As you said it is a common design.

Have you contacted the switch manufacturer for suggestions on how interface a switch in Linux? Please note that the davinci mdio was designed to connect a PHY and not a switch. When you contact the switch manufacturer they have a driver they recommend for you to use.

I would recommend taking a look at this file in the kernel documentation for more tips.

Documentation/devicetree/bindings/net/fixed-link.txt

Best Regards,

Schuyler

0 Avner Flesch over 4 years ago in reply to Schuyler Patton

Intellectual 385 points

Hi,

Thanks for the reply.

The reason I need this MDIO interface is to control the switch (with Marvell software).

Currently, I didn't manage to understand how to allow it with the devinvi_mdio driver, so, I figured a different solution:

I am using "mmap" to access the MDIO controller registers from the userspace.

Thus, I can use Marvell's software and manage the switch.

Thanks

Avner

0 Schuyler Patton over 4 years ago in reply to Avner Flesch

TI__Mastermind 40130 points

Hi,

Does the work for what you need?

Best Regards,

Schuyler

0 Avner Flesch over 4 years ago in reply to Schuyler Patton

Intellectual 385 points

Yes - it does.

I guess everyone who wants to manage Marvel switch with Marvell software package - can implement the required MDIO Read/Write with this method.

Thanks

0 Schuyler Patton over 4 years ago in reply to Avner Flesch

TI__Mastermind 40130 points

Hi,

Is there a link to documentation on how to do the implementation that you could post here?

Best Regards,

Schuyler

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AM3352: Linux - Activate MDIO driver with marvell switch 88E6341 (or other switch)