TUSB8041A: Can’t work if plug USB device during bios post display

Hi Daniel,

Power up timing requirements can be ignored if an active reset is applied to GRSTz, if only a capacitor is used to generate the reset pulse then 3.3V and 1.1V must ramp simultaneously or 1.1V before 3.3V,

Please remove R1915 this pullup will put the hub in TEST mode.

Does hub work if devices are not plugged in during BIOS post?

Regards,

JMMN

Hi Jmmn,

Thanks for your help.

We remove R1915 and pop R1914 PD at TEST pin.

But we have met the issue: If device not plugged in during bios post, after boot to bios menu, then plug in USB device and it can’t work.

Would you kindly help to advise debug suggestion?

Thanks.

Hi Daniel,

Does this problem only happen when the BIOS menu is active?   Does hot plug / unplug of devices work properly during normal (not bios) operation?

The USB drivers used while the BIOS is active are different than the standard USB drivers and they may not be checking for connect / disconnect interrupts from hubs.

What's the BIOS make?

Regards,

JMMN

Hi Jmmn,

We have seen USB device lost no matter bios post or boot to windows, issue happen randomly at different board.

We will check USB port eye diagram if meet spec and check with WST bios if any CPU USB setting can finetune for fix the issue.

Any other debug suggestion you can share with us?

BTW would you help to check if there have TUSB80XX USB 3.0 HUB qualified experience on AMD ROME platform?

Thanks

Daniel,

The TUSB80xx hubs have been implemented with AMD systems many times in the past.  It is unlikely a software fix is needed, interoperability problems are usually hardware related. 

Please check: 1)  the TUSB8041A has a solid ground plane connection through the thermal pad 2) USB_VBUS should only be high when there is an powered upstream host connection 3) confirm that there is no power supply droop to the device or on VBUS to the downstream ports 4) there should be ac coupling caps on the SS TX pairs of each port.

Regards,

JMMN

Hi Jmmn,

Thanks for help. Update our check result.

Also, customer like to know how to set in uEFI BIOS code, since they think this is maybe SW related issue.

The USB drivers used while the BIOS is active are different than the standard USB drivers and they may not be checking for connect / disconnect interrupts from hubs.

What's the BIOS make?

1)  the TUSB8041A has a solid ground plane connection through the thermal pad

Daniel: Yes, we have solid ground through the thermal pad as below picture

2) USB_VBUS should only be high when there is an powered upstream host connection

Daniel: Yes, we confirm the USB_VBUS level is normal

3) confirm that there is no power supply droop to the device or on VBUS to the downstream ports

Daniel: We confirmed, no power supply droop.

4) there should be ac coupling caps on the SS TX pairs of each port.

Daniel: Yes , we have coupling cap in each SS TX pair.

Thanks

Hi Daniel,

The  uEFI BIOS setting doesn't impact the hub directly, but it may impact the operation of the devices connected downstream if you need to boot from a drive.

Can you confirm if the problem is the downstream device not showing up when connected? Or is the problem that the downstream devices drop off the bus?

Also, does the problem only happen with BIOS or during normal operation?

How long is the trace length on the PCB?

Regards,

JMMN

Hi Jmmn,

Thanks for help.

Confirmed the information as below. Any other suggestion?

Q1: Can you confirm if the problem is the downstream device not showing up when connected? Or is the problem that the downstream devices drop off the bus?

A: During the uefi shell , can’t use the USB keyboard

Q2: Also, does the problem only happen with BIOS or during normal operation?

A: Happen in BIOS or in OS (normal operation)

Q3: How long is the trace length on the PCB?

A: SB2.0 : the total longer length is 7.8inch；USB3.0 : the total longer length is 7.0nch.

Thanks

Hi Daniel,

Those trace lengths should be ok.

Can you confirm if they boot with nothing connected to the hub and enter normal operating system, if they connect a USB keyboard - does it work?  Or it doesn't show up?

Regards,

JMMN

Hi Jmmn,

It is random fail on every downstream ports (1,2,3,4), no matter enter normal operating system or not.

Sometimes port1 fail, port2,3,4 OK, but after reboot, situation becomes port2 fail, port1,3,4 OK.

Are there any concern about our schematic on my first post?

Like we don't support battery charging, but we pull up all the control pins.

Thanks

HI Daniel,

Are all the downstream ports loaded?  If so can the customer try powering downstream VBUS from an external bench supply?  I have seen a similar behavior when 4 downstream devices are trying to power on simultaneously and the VBUS cannot handle the high current load.  

Regards,

JMMN

Hi Jmmn,

We have already confirmed the PCI location is “PCI bus 3, device 0, function 3”.(Fig.1) But when we executed this tool, we can’t see the HUB.(Fig2.)

Fig.1

Fig. 2

Thanks