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3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Mon Mar 19, 2018 11:24 am
by 9pi
Announcements of the 3B+ refer to the new USB hub / ethernet chip as a LAN7515, and indeed the chip on my board is labelled LAN7515. In order to adapt the Plan 9 operating system for the 3B+, I spent the weekend writing and attempting to debug a lan75xx driver. Without success.

The device enumerates on the USB as 0424/7800, and the chip-id register reads 0x7800. I should have realised sooner that this might not be consistent with a 75xx series device. And indeed, when I tried booting Raspbian, the dmesg output included

Code: Select all

usbcore: registered new interface driver lan78xx
In the source for building the .dtb files there's a bcm-283x-rpi-lan7515.dtsi which contains the line

Code: Select all

compatible = "usb424,7800";
so this does seem to be the anticipated device ID.

It appears that the ethernet core of the LAN7515 is compatible with the LAN7800 and not the LAN7500. Can that be right?

Re: 3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Mon Mar 19, 2018 11:36 am
by jamesh
That is correct.

The driver you need is the lan78xx

I have no idea why that is the case though. The naming of the chip is a little odd.

The driver for the old chip is the smsc75xx

Re: 3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Mon Mar 19, 2018 12:04 pm
by 9pi
The driver for the old chip is the smsc75xx
I think ithat should be smsc95xx -- I had to write a Plan 9 driver for that chip when the pi3 first came out. Unfortunately some of the registers for the lan78xx are quite different.

Re: 3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Mon Mar 19, 2018 3:58 pm
by jamesh
9pi wrote:
Mon Mar 19, 2018 12:04 pm
The driver for the old chip is the smsc75xx
I think ithat should be smsc95xx -- I had to write a Plan 9 driver for that chip when the pi3 first came out. Unfortunately some of the registers for the lan78xx are quite different.

Sorry, typo! You are correct, the smsc95xx.

Re: 3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Fri Apr 27, 2018 1:55 pm
by c7borg
Do you know where I can get the lan78xx driver? does it come in a .deb type file?

I'm trying to run Jessie on a 3b+ it boots fine but just gets a 169.x.x.x address, I'm guessing it's driver related

Re: 3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Fri Apr 27, 2018 2:55 pm
by 6by9
c7borg wrote:
Fri Apr 27, 2018 1:55 pm
Do you know where I can get the lan78xx driver? does it come in a .deb type file?

I'm trying to run Jessie on a 3b+ it boots fine but just gets a 169.x.x.x address, I'm guessing it's driver related
It's part of the Linux kernel - https://github.com/raspberrypi/linux/bl ... /lan78xx.c

Re: 3B+ ethernet: is it LAN75xx or LAN78xx ?

Posted: Fri Apr 27, 2018 7:10 pm
by jamesh
c7borg wrote:
Fri Apr 27, 2018 1:55 pm
Do you know where I can get the lan78xx driver? does it come in a .deb type file?

I'm trying to run Jessie on a 3b+ it boots fine but just gets a 169.x.x.x address, I'm guessing it's driver related
169..... usually means a DHCP failure somewhere.