Hey!
I’m using LX2162A SOM (rev 1.1) + LX2162A Clearfog board (rev.2). So these are the most recent HW revisions for this time.
I connected and configured DAC cable to dpmac.5 and dpmac.6 (due to article https://solidrun.atlassian.net/wiki/spaces/developer/pages/199131187/ClearFog+LX2162A+Quick+Start+Guide) - and everything works ok. Both ethernet interfaces are up and running.
Then I did the same with SFP+ optical cable - linux was not able to read EEPROM inside SFP+ modules and the link was down:
[ 504.572693] sfp sfp-at: please wait, module slow to respond
[ 560.864692] sfp sfp-at: failed to read EEPROM: -6
I’ve found 2 HW bugs with LX2162A clearfog board:
-
Low 3.3 voltage on the board. I got only 2.6V instead of 3.3V.
Due to schematics 3.3V is passed through BAT54C diode D48 which has about 800mV forward voltage drop at 100mA:
So i have 3.3V at point 1 and 2.6V at point 3. This is extremely low for EEPROM inside SFP+ transceivers - thats why EEPROM is not functional. Also this 3.3V (2.6V in fact) is feeding usb hub + marvell phy chip (haven’t tested them yet).
I’ve shorted points 1 and 3 on diode D48 and got true 3.3V on the board. After that linux was able to read EEPROM inside SFP+ module.
But link was still down. -
TX_DISABLE (AT_TX_DIS) pin on SFP+ connector is left floating (not connected to anywhere).
This means that SFP+ transceiver is turned off. I tied this pin to ground and after that i got fully functional SFP+ optical connection.
@jnettlet - please address these bugs.