VBUS race condition where USB TypeC 'attach' event is never seen by the application

[intercreate]

Overview Possible issue in the Middleware USB-PD G0 Device section

Describe the set-up

• Custom board where BSP_PWR_VBUSGetVoltage() senses TypeC voltage.
• arm-none-eabi-gcc (GNU Tools for Arm Embedded Processors 7-2018-q2-update) 7.3.1 20180622 (release) [ARM/embedded-7-branch revision 261907]

Describe the bug Possible issue in USB PD Middleware Device for G0. At attach sensing time, the library should check for VBUS to stabilize to Vsafe5V before moving forward. However, I believe there's an incorrect conditional for this check.

How To Reproduce

1. Have a system with relatively fast VBUS ramp (less than CAD_TPDDEBOUCE_THRESHOLD)
2. Attached a USB PD compliant device
3. No attach event occurs.

Additional context This patch gets me past this issue.

iff --git a/Middlewares/ST/STM32_USBPD_Library/Devices/STM32G0XX/src/usbpd_cad_hw_if.c b/Middlewares/ST/STM32_USBPD_Library/Devices/STM32G0XX/src/usbpd_cad_hw_if.c
index 0209bb8..3068df8 100644
--- a/Middlewares/ST/STM32_USBPD_Library/Devices/STM32G0XX/src/usbpd_cad_hw_if.c
+++ b/Middlewares/ST/STM32_USBPD_Library/Devices/STM32G0XX/src/usbpd_cad_hw_if.c
@@ -766,7 +766,7 @@ static uint32_t ManageStateAttachedWait_SRC(uint8_t PortNum, USBPD_CAD_EVENT *pE

   if ((_handle->CurrentHWcondition != HW_Detachment) && (_handle->CurrentHWcondition != HW_PwrCable_NoSink_Attachment))
   {
-    if ((BSP_PWR_VBUSGetVoltage(PortNum) > BSP_PWR_LOW_VBUS_THRESHOLD)
+    if ((BSP_PWR_VBUSGetVoltage(PortNum) < BSP_PWR_LOW_VBUS_THRESHOLD)^M
         && (USBPD_PORTPOWERROLE_SRC == Ports[PortNum].params->PE_PowerRole))
     {
       /* reset the timing because VBUS threshold not yet reach */

[intercreate]

There doesn't seem to be any notification to the user that an attach event timed out. I would expect one from USBPD_DPM_Notification() maybe?

Also, as a reminder, USBPD_VbusEnable() library callback is called before this conditional statement, hence there is a race condition.

[ALABSTM]

Hi InterCreate,

Thank you for this one new aspect you pointed out. I let @bouattay check what you described and provide answers.

With regards,

[ALABSTM]

Hi InterCreate,

Our development teams said your issue is valid and that it is already known. It has been fixed internally and shall be made available in the frame of a future firmware package release. Unfortunately, we cannot share a date for the moment. We will be back to you as soon as this is done.

With regards,

[ALABSTM]

ST Internal Reference: 59814