We designed our board with iMX6Q and measured USB client full-speed eye-diagram.
The USB signal voltage level in full-speed cannot reach 3.3V. USB traces impedance is 90 ohm differential controlled.
We tried to increase amplitude with setting register USBPHY1.TX.D_CAL=0x0 by memtool.
The amplitude of full-speed USB signal increase a little but still cannot reach 3.3V. It only has around 2.6V amplitude. (Refer to attached bmp file)
Any other software suggestion ?