TUSB8044A: Cannot detect USB3.0 Hub.

Hi  Ohshita:

    Can you send schematic for review?

Best

Brian

Hi Brian,

I can send schematic,
but the schematic is confidential.

If possible, could you contact me at my email address?

Best regards,
Y.Ohshita

Please accept my friendship request and send schematic  though  private message.

Best

Brian

When can you send schematic?

Best

brian

I will close the ticket since no update.

Best

Brian

Hi Brian,

Sorry for the late reply.

I sent an email on August 20th because I need some information to send schematic.
Please check the email.

ok, I just replied your email.

Best

Brian

is customer ok to send schematic?

Best

Brian

Hi Brian,

Thank you for replying to an email.
I will send schematic by the end of September.
Please wait for a little while longer.

Best regards,
Y.Ohshita

sure, we can wait.

Best

Brian

waiting for schematic

Hi  Ohshita::

   I didn't see major issue   from schematic.

   Can customer take waveform  from 3.3v/1.1v/GRST signal?

   When issue happens, did crystal still osculating?

Regards

Brian

Hi Brian,

I took waveform at power-on, I will send it by email.
Yes, crystal is osculating When issue happens.

When issue happened, host can only detect USB2.0 hub,
so I observed waveform of USB3.0 signal between host and hub(TUSB8044A).

TX(host->hub) is outputting LFPS, but the frequency of RX(hub->host) signal is 5Gbps.
There seems a mismatch between host and hub in LTSSM state during link training.

Best regards,
Y.Ohshita

Hi Ohshita:

  Can you make sure which TX send LFPS signal, which TX send 5Gbps?

  Power supply waveform looks fine

Best

Brian

Hi Brian,

I took waveform of USB3.0 signal between host and hub(TUSB8044A).
I will send waveform by email.

Best regards,
Y.Ohshita

Hi  Ohshita-san:

    From waveform, it seems hub entering compliance mode ( sending 5G signal ). This could happen when host  is not active yet during power cycle but USB_VBUS is already connected.

Best

Brian

Hi Brian,

Is there a way to check whether TUSB8044A is entering in compliance mode or not?

Best regards,
Y.Ohshita

Hi  Ohshita-san:

   USB analyzer should able to detect it is compliance mode or not. But from your system,  I don't think you can connect USB analyzer between host and hub.

    But from the waveform you took, hub  seems entered compliance mode. 

Best

Brian

Hi Brian,

Thank you.
I also think that we cannot connect USB analyzer between host and hub in our system.

I have two questions.

1.  Why does hub enter compliance mode when USB_VBUS is connected before host becomes active?
2. In our system, USB_VBUS is always connected before host becomes active when power on.
   What reasons could you consider of differences between when hub enters compliance mode and when it does not?

Best regards,
Y.Ohshita

Ohshita Yoshihiro said:

Why does hub enter compliance mode when USB_VBUS is connected before host becomes active

. If this is an embedded design, but when the host is “disabled”  it leaves its  hub receiver terminations enabled and USB_VBUS is high, the hub could enter compliance mode.  

Ohshita Yoshihiro said:

What reasons could you consider of differences between when hub enters compliance mode and when it does not?

in compliance mode, hub TX will keep sending compliance pattern.

in normal mode, TX output pattern should be change over time, like idle signal.

Best

Brian

Hi Brian,

Brian Zhou said:

If this is an embedded design, but when the host is “disabled”  it leaves its  hub receiver terminations enabled and USB_VBUS is high, the hub could enter compliance mode.  

Does this behavior occur with general hub devices?
Or is it specification of TUSB8044A?

When issue happened, I found that it can be recovered by following procedure.

Once, set bit4(USB2.0_only) of Device Configuration Register 3(Offset 25h) to 1b via I2C,
Then return this bit to 0b.

Is this valid recovery method?

Best regards,
Y.Ohshita

Ohshita Yoshihiro said:

Does this behavior occur with general hub devices?

it could be occur for general hub devcies.

Ohshita Yoshihiro said:

Once, set bit4(USB2.0_only) of Device Configuration Register 3(Offset 25h) to 1b via I2C,
Then return this bit to 0b.

this bit disabled USB3 hub in compliance mode and reset  USB3 hub  again, this is a valid recovery method.

Best

Brian

Hi Brian,

Thank you.
It is very helpful for our system to have valid recovery method.

In our system, changing to connect USB_VBUS after host becomes active is very difficult.
Instead, it is possible to de-assert GRSTz after host becomes active.
Can issue be improved with this method?

Best regards,
Y.Ohshita

it should , did you try?

Best

Brian

Hi Brian,

No, not yet.
Since GRSTz is controlled by CPLD, We need to modify RTL.
I will try, once it is ready.

Best regards,
Y.Ohshita

please keep me .update.

Best

Brian