USB downstream of USB hub did not work when test with i.MX6DQ port test control.

[satoshishimoda]

Hi community,

Our partner have a question about i.MX6DQ USB compliance test.

They executed the test with USBC_n_PORTSC1 register setting, but the downstream of USB hub did not work well with the following connection even though it worked well without USB hub.

i.MX6Q -> USB Hub -> USB device

[Question]

Would you let me know why the downstream of USB hub did not work?

Best Regards,

Satoshi Shimoda

[b36401]

From a general point of view USB hub is more complex device that Ethernet hub.

It has buffers for date and it can "convert" the flow from one USB version to another.

So I suppese it may slow the flow if the hup has weak processor or memory.

Also I can surmise that i.MX6Q polls USB hub less often than USB device.

But it is just an assumption.

[satoshishimoda]

Hi Victor,

Could you get information about difference between i.MX51 and i.MX6Q USB controller?

We have to resolve this problem to pass USB compliance test.

Best Regards,

Satoshi Shimoda

[satoshishimoda]

Hi Victor,

I got a new information.

i.MX51 can do USB compliance test even though through USB hub, it is same hub used for i.MX6DQ system.

So our partner guess there is some difference between i.MX51 and i.MX6DQ.

Best Regards,

Satoshi Shimoda

[satoshishimoda]

Dear Victor,

Thank you for your reply, and sorry for delay.

According to your reply, I feel there is a possible to improve this problem by changing the usb hub to other products.

So I will tell your comment and propose testing with other usb hub to our partner.

Best Regards,

Satoshi Shimoda

[satoshishimoda]

Hi Victor,

Would you give me a comment about the difference between i.MX51 and i.MX6DQ?

Best Regards,

Satoshi Shimoda