Operating System

Windows 10

Board

Custom STM32H747BGT6

Firmware

Custom firmware with use of TinyUSB lib. Affected file: src/portable/synopsys/dwc2/dcd_dwc2.c

What happened ?

dcd_dwc2.c - function reset_core() halts in infinite loop after restart or power up of MCU. It happens at random times.

Present code:

static void reset_core(dwc2_regs_t * dwc2)
{
  // reset core
  dwc2->grstctl |= GRSTCTL_CSRST;

  // wait for reset bit is cleared
  // TODO version 4.20a should wait for RESET DONE mask
  while (dwc2->grstctl & GRSTCTL_CSRST) { }     // <<---- Software halts here

  // wait for AHB master IDLE
  while ( !(dwc2->grstctl & GRSTCTL_AHBIDL) ) { }

  // wait for device mode ?
}

Solution:
As per ST reference manual RM0399 page 2011: The software must also check that bit 31 in this register is set to 1 (AHB Master is Idle) before starting any operation.

Also in HAL original library mentioned check is carried out before reset operation (see: function USB_CoreReset in stm32h7xx_ll_usb.c)

Proposal for corrected code:

static void reset_core(dwc2_regs_t * dwc2)
{
  // wait for AHB master IDLE
  while ( !(dwc2->grstctl & GRSTCTL_AHBIDL) ) { }

  // reset core
  dwc2->grstctl |= GRSTCTL_CSRST;

  // wait for reset bit is cleared
  // TODO version 4.20a should wait for RESET DONE mask
  while (dwc2->grstctl & GRSTCTL_CSRST) { }

  // wait for device mode ?
}

How to reproduce ?

Error happens randomly during restart or powering up of uC.

Debug Log as txt file (LOG/CFG_TUSB_DEBUG=2)

N/A

Screenshots

No response

I have checked existing issues, dicussion and documentation

• I confirm I have checked existing issues, dicussion and documentation.