USB and pwr.vos0

[dlancea]

I've been having an issue with setting up USB with this library. Using the usb_device crate the device setup fails about half the time at the final call to build():

#[allow(static_mut_refs)] 
let usb_bus = UsbBus::new(usb, unsafe { EP_MEMORY.assume_init_mut() });

// let mut serial = usbd_serial::SerialPort::new(&usb_bus);
let mut midi_class = UsbMidiClass::new(&usb_bus, 1, 1).unwrap();

let usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0x16c0, 0x5e4))
	.device_class(0)
	.device_sub_class(0)
	.strings(&[StringDescriptors::default()
		.manufacturer("Music Company")
		.product("MIDI Device")
		.serial_number("12345678")])
	.unwrap();

let mut usb_dev = usb_dev.build(); // <- Fails here

defmt::info!("Built!");

The problem is this line: https://github.com/stm32-rs/synopsys-usb-otg/blob/master/src/bus.rs#L448 The Soft Reset fails to complete about half the time.

I am ensuring the appropriate timers are set before the call to build():

ccdr.peripheral.kernel_usb_clk_mux(stm32h7xx_hal::rcc::rec::UsbClkSel::Hsi48);
let _ = ccdr.clocks.hsi48_ck().expect("HSI48 must run");
let _ = ccdr.clocks.hse_ck().expect("hse_ck must run");

The problem seems to be tied to the pwr.vos0 power setting and the 480MHz clock. If i change the library to use default power settings and a system clock of 400MHz the problem seems to go away.

Here's a test file I've been using to illustrate the problem: https://gist.github.com/dlancea/0008a8618da3affb934e73ac04a3d35d (this doesn't use this library directly, but uses the same vos0/480MHz setup).

If anyone has advice on how I might get that 80MHz back it would be appreciated!

[phoracek]

Hey @dlancea. I see this other Daisy crate has an USB example. You may want to give it a try to see if it produces better results: https://github.com/CorvusPrudens/libdaisy-rust/blob/main/examples/usb_midi.rs

[dlancea]

That file (or the original from mtthw-meyer) was more or less my starting point.

I don't see that library accounting for this issue. I can't get that example to run, it seems to use the same outdated version of usb_device and usbd-midi the mtthw-meyer did, while not accounting for the changes.

I suspect that author has not checked that example works in a long time, if ever.

[phoracek]

Too bad. If you haven't yet, I'd recommend asking in the Daisy Discord's #rust channel. And if you don't get help there, you could compare the Rust code with whatever is being done around USB and clock in libDaisy.

[phoracek]

I've been looking into this today and found stm32-rs/stm32h7xx-hal#503 (comment). Overwriting the synopsys-usb-otg with the linked branch resolved the issue for me:

[patch.crates-io]
synopsys-usb-otg = { git = "https://github.com/AetherWareFoundation/synopsys-usb-otg", branch = "work-h7coreresethang" }