i.MX6 Plus - USB is unstable issue

yen-polin · ‎04-26-2016

Hi ,

We've implement i.MX6 Dual plus/Quad plus and Yocto 1.8 .

USB port of HOST/OTG are unstable at both Dual plus and Quad plus .

If we try to do "time dd if=/dev/sda1 of=/dev/null bs=8k" , then sometimes show the message as below

==> "usb 1-1: reset high-speed USB device number 2 using ci_hdrc" .

==> "Buffer I/O error on device sda1"

==> "usb 1-1: device firmware changed"

So we've measure the USB signals and power , the report as attached file looks fine .

Also we try to reduce USB trace length (under 1200mils) , but still can't fix this issue .

So

(1) Does it have any power rail for internal USB logic , we need to double confirm ?

(2) Do you have any suggestion about USB Test item (EL_xx) we need to check , if we'll measure Hi-Speed USB signals again ?

(3) Does it have any register cause these wrong message ? Could we try to disable it ?

(4) Other recommend ?

Thanks a lot.

Terry

yen-polin · ‎05-05-2016

Hi ,

I've change the value of address: 0x021b0400 to 0x14420000 from 0x514201f0 ,then it can fix this USB issue .

Address : 21B_0400 is MMDC Core AXI Reordering Control Register .

Thanks a lot.

igorpadykov · ‎04-27-2016

Hi Terry

reason for instability may be VDD_VBUS_CAP -power rail for internal USB logic,

as well as DDR errors, so recommended to test it with ddr test:

AN4589 Configuring USB on i.MX 6 Series Processors

on p.7 shows setting for improving usb signals

Also one can check sect.3.11 USB recommendations

i.MX6 System Development User’s Guide

Best regards

igor

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