Linux/PROCESSOR-SDK-AM335X: usb VBUS_ERROR in ti sdk 03_03_00_04

Hi Liang,

If VBUS drops below 4.4 volts the USB subsystem in AM335x will assume an over-current condition and disconnect. The product design must insure VBUS does not drop below 4.4 volts because that is considered the minimum voltage for VBUS to be valid.

See the below e2e threads for details:

e2e.ti.com/.../589783
e2e.ti.com/.../476837
e2e.ti.com/.../324491
e2e.ti.com/.../593133

Regards,
Pavel

Hello Pavel:
we remove the drvvbus control of am335x and make tps2051B output 5V directly to my lan9500ai.
At first it work seems fine,but later
It report that VBUS_ERROR in a_host (89, <AValid), retry #1, port1 00000507
We have use the scope to capture the VBUS which connect to the am335x ,there is no drop ,it always 5.1v .
I look through the bf527 datasheet which also use the musb,
the VBUS ERROR mean VBUS below VBUS Valid threshold detected (valid when USB is 'A' device)
a_host (89, <AValid) should mean that the devctl register 1 - 'B' device detected 11 - Above VBUS valid
I guess the am335x musb turn to B device。
The voltage should above the valid thredhold.
Why there is VBUS error?
Regards
wangl

Please post the usb portion of the schematics for review.
Please ensure you have a minimum 120uF CAP on the VBUS line, this is required in the USB Spec for USB host port.

hi Bin:

Is it fine to add an 220uF cap on the VBUS line?And can you tell me which spec define the requirement?

Though there is no 120uF cap on VBUS line,I remove the FB26 ,I add the +5v from DC regulated power supply to C214, VBUS should  never drop.

But it report the 0x89   VBUS_ERROR   in a_host(89, <AValid).

Is there any other reason for it become a B device?

I will add the 220uF cap to our other boards parralel with C169 ,is it correct?Or I add the the cap to parralel with c171?

Best regards

wangl.

The 120uF CAP is needed no matter how the input power source to the power switch is connected. The cap is for compensating the inrush current while usb device attaching which could cause VBUS_ERROR.

Please add the cap next to C171, not to C169. It should be on the output side of the power switch, so that USB1_VBUS pin can sense it.

BTY, R60 and R61 are too big for grounding the USB ID pin, please replace them with 0R resisters.

LIANG WANG102707 said:

Is it fine to add an 220uF cap on the VBUS line?And can you tell me which spec define the requirement?

hi Bin :
We have done the change add the CAP and use an stable power chip for usb before the tps2051,howerver ,it come out again.

When we do the high temperature test of our board in 70 degree 
It report
[11.969571]dsps_interrrupt 360 VBUS error workaround(delay coming)
[12.065857] musb-hdrc musb-hdrc.1.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #1,port1 00000100
[12.119341] musb-hdrc musb-hdrc.1.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #2,port1 00000104
[12.172778] musb-hdrc musb-hdrc.1.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #3,port1 00000104
I look the code the differece between the interrupt flag of the past is the
1 << wrp->drvvbus.
what is the mean of this bit set?
Why there is still this error?

Regards
wangl

Hello,

1) Does this issue occur at all temperatures, or only at high-temp?

2) What percentage of boards are affected by this issue?

>>Do you mean after added the VBUS CAP, the VBUS error only happens in high temperature, but not in normal temperature?
after added the VBUS CAP, [11.969571]dsps_interrrupt 360 VBUS error workaround(delay coming) come out in high temperature.
it is come out on usb1, The usb0 is configure as usb host with A connector.The usb1 is connect with lan9500 in our system.
but I do see the lan9500 is enumerate fine later.
But I ask our hardware guy,they said that they do not have 220uF cap ,they use two 100uF cap instead for usb0 and usb1 ,is it fine?
>>wrp->drvvbus is defined in am33xx_driver_data in musb_dsps.c, it is the bit field for the DRVVBUS interrupt.
why this bit is set ?When this bit set ,what does it mean?Is it mean DRVVBUS pin can not be set to high level by hardware?
The technical reference manual said that "The control on the USB_DRVVBUS is automatic and is handled by the USB controller."
Why there is such interrupt occured?

There is still such error in normal temperature:
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #1,port1 00000100
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #2,port1 00000100
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #3,port1 00000104
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(88,<AValid),retry #3,port1 0000010c
and then I insert the usb disk ,the system can not recognize the usb new device insert.

LIANG WANG102707 said:

>>wrp->drvvbus is defined in am33xx_driver_data in musb_dsps.c, it is the bit field for the DRVVBUS interrupt.
why this bit is set ?When this bit set ,what does it mean?Is it mean DRVVBUS pin can not be set to high level by hardware?
The technical reference manual said that "The control on the USB_DRVVBUS is automatic and is handled by the USB controller."
Why there is such interrupt occured?

While the MUSB controller enters the host mode, it enables USBx_DRVVBUS pin to turn on the VBUS power switch, and the controller also generates the DRVVBUS interrupt to notify the software.

LIANG WANG102707 said:

There is still such error in normal temperature:

So the 220uF CAP doesn't change any of the symptom, right? Just trying to understand if you mentioning high-temp is anything new or not.

I am unable to think of any other reason why VBUS error happens. Please use a scope to probe the AM335x USB1_DRVVBUS and USB1_VBUS pins simultaneously to see if there is any VBUS drop.

LIANG WANG102707 said:

There is still such error in normal temperature:
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #1,port1 00000100
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #2,port1 00000100
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(89,<AValid),retry #3,port1 00000104
musb-hdrc musb-hdrc.0.auto :VBUS_ERROR in a _wait_vrise(88,<AValid),retry #3,port1 0000010c

Wait a minute, this message happens on USB0 port, which has nothing connected, right? You don't see this message on USB0 port before adding the VBUS CAP on USB1 port?

Did you add CAP on USB0 port as while, since USB0 is also a host-only port?

>>Wait a minute, this message happens on USB0 port, which has nothing connected, right? You don't see this message on USB0 port before >>adding the VBUS CAP on USB1 port?
There is a industry USB disk connected on usb0 when it boot ,but the host do not recognize the usb
There is two 100uF cap on the usb0 port too.

>>So the 220uF CAP doesn't change any of the symptom, right?
It seems does not change. The" dsps_interrupt 360 :VBUS error workaround " happen almost in high temperature.
But it also come out in normal temperature .

Is there anyway to change the code to configure the musb as usb host directly and do not change otg role according to the VBUS?

I want to change the hardware to output directly without the control of VBUSDRV

Can you please answer DK's query "What percentage of boards are affected by this issue"?

LIANG WANG102707 said:

Is there anyway to change the code to configure the musb as usb host directly and do not change otg role according to the VBUS?

I want to change the hardware to output directly without the control of VBUSDRV

The USB controller on AM335x is a dual-role controller, some of the role changing work is done in the hardware, so there is no true host-only mode.

The VBUS error is detected in the hardware, removing DRVVBUS control doesn't solve the issue. We should figure out the root cause of the issue so that we will know how to properly fix it.

>>1) Does this issue occur at all temperatures, or only at high-temp?
as I said in last reply ,it occur at all temperature ,but the mostly in high temperature.
>>2) What percentage of boards are affected by this issue?
the percentage is meaningless.

Because we only have 9 boards can work.

Only one board do not meet the VBUS error before add the cap and DC regulator in the high temperature test.
we only test two board in high temp environment after add the cap and DC regulator.
The one never meet the VBUS error also report the dsps vbus error and drvbus interrupt after add the cap and DC regulator in the high temperature test.

It means 100%.

Do you mean the VBUS error is hardware problem?
Is there any method to debug in the kernel?Or do you have any idea how to fix it?
Is it an usb bug in kernel?Or it is an hardware bug in usb controller?

LIANG WANG102707 said:

Do you mean the VBUS error is hardware problem?
Is there any method to debug in the kernel?Or do you have any idea how to fix it?
Is it an usb bug in kernel?Or it is an hardware bug in usb controller?

It is an VBUS error condition reported by the hardware, in which the VBUS drops below 4.4v. The common root cause is the VBUS doesn't have enough capacitance as required in the USB Spec. I don't think it is a kernel bug.

Please boot the board without any usb devices connected to USB0 and USB1 port, and hook up the scope probes to USBx_DRVVBUS and USBx_VBUS pins where close to AM335x, then plug in the USB device and use the scope to capture the signals of the two pins. We want to check if USBx_VBUS indeed drops while the USB device is attached.

Hello Bin:
I have do the high temp again myself .
When I use drvvbus to control the output of VBUS_USB to am335x ,I do found that there is an pulse of drvbus.
The drvvbus jump from low to high ,then VBUS_USB is 5V.
But VBUS_USB jump to below 4.4v soon ,then drvvbus jump from high to low.
Then VBUS_USB is 0v steady,and drvbus is low steady.
Then I check the kernel output " dsps_interrupt 360 :VBUS error workaround ".
This is correct according to your opinion.

But what I strange is that when I do not use drvvbus to control the output of VBUS_USB,
i make the tps2051 pin 4 hight to output VUSB_USB directly to am335x ,
there is do no fall below 4.4v on scope .
But there is still error like following and the lan9500 do not work.
[ 13.806475] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_wait_vrise (81, <SessEnd), retry #1, port1 00000104
[ 13.958900] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_wait_vrise (81, <SessEnd), retry #2, port1 00000104
[ 14.263741] musb-hdrc musb-hdrc.1.auto: VBUS_ERROR in a_wait_vrise (80, <SessEnd), retry #3, port1 0008010c
Does the VBUS_USB need some power and the current supply of our board is not big enough to enable the host feature?

Can you give me some idea?
Best regards

I have sent you the friendship request, which has my email address. Please email me your board schematics. What is the Processor SDK version you use?