The tuning guide is correct.
- Adjust HS_CURR_LEVEL register as described in the “Tuning Procedure” section (Note: maximum allowable offset: +/-6 steps). You can write the value you want to it .
- Provide the “tuned offset value” to software team. Calculate the offset steps and provide to sw team .
"For example, if they’re tuning USB Port 1, they should read bits 16:11 of address 0x038201F0 (FUSE_USB_CALIB) to get the default (or starting) value.
Then, if say their default/starting value was 0x20 and they noticed writing a value of 0x1C improved their eye and the test passed. Then they know that their board requires an offset of “-4”.
They should then let their software team know so they can add a “-4” offset to their software implementation.
Once it’s implemented into their software, they should verify it’s done correctly - ie when they load their new software, when they read bits 16:11 of address 0x038201F0 (FUSE_USB_CALIB) for that particular board they were testing with, they should now get a value of 0x1C.
Customer can then try a few more boards to ensure this new offset allows the eye test to pass."