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Digital Tuning with Inverted LVDS

Question asked by rmd91 on May 9, 2016
Latest reply on Jun 6, 2016 by rmd91



I'm having trouble passing digital tuning using an FMCOMMS3 on FMC carrier board with a ported reference design. The carrier flips several of the differential pairs on FMC connector. I figured that was okay since the AD9361 can be programmed to invert these pairs with registers 0x3D and 0x3E. So far, I've tried:


1. Letting tuning fail, writing 0x3D/0x3E after boot and retuning.

    This didn't work for me, as the driver probe fails and I don't get the digital_tuning file in the debug driver.


2. Skip tuning with the "adi,digital-tuning-interface-tune-skip-mode=2" setting in the Devicetree.

    I can boot and load the driver with this, but running echo 0 3 > digital_tune seems to do nothing. According to guides on this site, I should have the tuning results in dmesg, but I don't them. Perhaps it doesn't run in this mode?


3. Setting adi,lvds-invert1/2-control in the Devicetree.

    The driver probe still failed on tuning.


What would be the best way forward to address the inverted bits? In particular, how can I better debug my setup?