[stm32] Wait until the PHYC PLL is stable

[salkinium]

Describe the PR

Thank you for this awesome project, very enjoyable to work with!

I've been integrating TinyUSB using custom firmware on the STM32F723E-DISCOVERY board and got stuck in reset_core when initializing the HS port. Waiting 2ms after PLL enablement fixes this issue.

Additional context

The solution for this was already discovered in https://github.com/hathach/tinyusb/issues/2074#issuecomment-2597894247, where the CubeHAL waits 2ms, since there's no USB_HS_PHYC_PLLRDY bit in the USB_HS_PHYC peripheral

Closes #2074.

[salkinium]

Unfortunately no, the RM0431 p1560 does not mention anything about PLL stability.

The CubeHAL code is here though

[hathach]

#2074 is tested with h747, which I don't think have USB_HS_PHYC as F723, therefore it is probably another issue. I also have the F723 discovery and has no issue with stocked examples. Can you make an minimal changes to oone of stock example that coould cause the issue ?

[HiFiPhile]

👀 Me too I didn't have this issue on STM32F723E-DISCOVERY, with both IAR 8.3 and GCC 12.3 compilers.

[salkinium]

Ah, well… at first I also couldn't reproduce this issue with the tinyusb examples, until I power cycled the board:

cd tinyusb
python3 tools/get_deps.py stm32f7
cd examples/device/cdc_msc
rm -rf _build; \
    make BOARD=stm32f723disco RHPORT_DEVICE=1 LOG=2 all && \
    openocd -f board/stm32f7discovery.cfg -c "program _build/stm32f723disco/cdc_msc.elf verify reset exit"

*power cycle board*

picocom --imap lfcrlf -b 115200 /dev/tty.usbmodem103

*reset board*

USBD init on controller 1, speed = Full
sizeof(usbd_device_t) = 56
sizeof(dcd_event_t) = 12
sizeof(tu_fifo_t) = 12
sizeof(tu_edpt_stream_t) = 20
CDC init
MSC init
guid, gsnpsid, ghwcfg1, ghwcfg2, ghwcfg3, ghwcfg4
0x00003100, 0x4F54330A, 0x00000000, 0x229FE1D0, 0x03EED2E8, 0x23F00030
Highspeed UTMI+ PHY init
<----- gets stuck here in reset_core

If you then apply my patch, it progresses past the reset. If you then undo my patch it also progresses past this step until a power cycle.

So something related to the PLL in the DWC2 core is sticky? Or it's an issue with GCC 14:

 $ arm-none-eabi-gcc --version
arm-none-eabi-gcc (Arm GNU Toolchain 14.2.Rel1 (Build arm-14.52)) 14.2.1 20241119

EDIT: Nope, I tried this exact procedure with GCC12 and GCC13 and the behavior does not change. EDIT2: Here is the failing ELF file compiled with GCC14, and here is the ELF file with my patch.

[HiFiPhile]

I still can't reproduce the issue with your binary.

UART is connected from jumper CN6 to allow full power-off, no matter power cycle (cable unplug&re-plug) or press reset button it always runs correctly.

I'm wondering if it's related to chip/board revision, I have:

• MCU Rev A; PHL 7B 724
• Board MB1260-F723E-D03

[HiFiPhile]

@Lurcy38 Hi, do you know anything about this ?

[salkinium]

Hm, I have the exact same board and MCU revison as you… Well maybe just leave it open then in case others have the same issue, I'm using a patched TinyUSB version anyways.

[EminYagmahan]

We use three custom boards of the STM32F723IE. We have noticed sporadically that without the wait time, the initialization routine gets stuck forever. For this reason, we are also patching the TinyUSB repository with this PR. It would be helpful if the PR gets its way into master.