utime.sleep_ms does nothing useful when called with 0 milliseconds.

[nevercast]

While debugging #5344 I encounted a situation where utime.sleep_ms(0) did not free the GIL to another thread. This is because utime.sleep_ms(0) is a useless invocation that does nothing.

micropython/extmod/utime_mphal.c

Line 51 in b9ec603

if (ms > 0) {

STATIC mp_obj_t time_sleep_ms(mp_obj_t arg) {
    mp_int_t ms = mp_obj_get_int(arg);
    if (ms > 0) {
        mp_hal_delay_ms(ms);
    }
    return mp_const_none;
}

I propose that at the very least this function calls MICROPY_EVENT_POLL_HOOK when ms is zero, and at best, always calls mp_hal_delay_ms. I don't believe zero should be a special case.

[dpgeorge]

I don't believe zero should be a special case.

I agree. It should have "continuous" behaviour for sleep_ms(x) where x tends to 0.

[dpgeorge]

Fixed by db6d60b