xtensa-lx-rt: Re-enabling hw-fp after ISR doesn't seem to work

[bjoernQ]

Example to be run on e.g. ESP32-S3

//! This shows how to use the TIMG peripheral interrupts.
//!
//! There is TIMG0 which contains a general purpose timer and a watchdog timer.

//% CHIPS: esp32 esp32c2 esp32c3 esp32c6 esp32h2 esp32s2 esp32s3

#![no_std]
#![no_main]

use core::cell::RefCell;

use critical_section::Mutex;
use esp_backtrace as _;
use esp_hal::{
    clock::ClockControl,
    interrupt::{self, Priority},
    peripherals::{Interrupt, Peripherals, TIMG0},
    prelude::*,
    system::SystemControl,
    timer::timg::{Timer, Timer0, TimerGroup},
};

static TIMER0: Mutex<RefCell<Option<Timer<Timer0<TIMG0>, esp_hal::Blocking>>>> =
    Mutex::new(RefCell::new(None));

#[entry]
fn main() -> ! {
    let peripherals = Peripherals::take();
    let system = SystemControl::new(peripherals.SYSTEM);
    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();

    let timg0 = TimerGroup::new(peripherals.TIMG0, &clocks);
    let timer0 = timg0.timer0;
    timer0.set_interrupt_handler(tg0_t0_level);

    interrupt::enable(Interrupt::TG0_T0_LEVEL, Priority::Priority1).unwrap();
    timer0.load_value(500u64.millis()).unwrap();
    timer0.start();
    timer0.listen();

    critical_section::with(|cs| {
        TIMER0.borrow_ref_mut(cs).replace(timer0);
    });

    let delay = esp_hal::delay::Delay::new(&clocks);

    let mut i = 0;
    loop {
        delay.delay_millis(1500);
        esp_println::println!("Let's do some math");
        esp_println::println!("{}", i as f32 * 2f32);
        i += 1;
    }
}

#[handler]
fn tg0_t0_level() {
    critical_section::with(|cs| {
        esp_println::println!(
            "Interrupt at {} ms",
            esp_hal::time::current_time()
                .duration_since_epoch()
                .to_millis()
        );

        let mut timer0 = TIMER0.borrow_ref_mut(cs);
        let timer0 = timer0.as_mut().unwrap();

        timer0.clear_interrupt();
        timer0.load_value(500u64.millis()).unwrap();
        timer0.start();
    });
}

Output:

Interrupt at 674 ms
Interrupt at 1174 ms
Interrupt at 1674 ms
Let's do some math



Exception occured 'Cp0Disabled'
Context
PC=0x4200100b       PS=0x00060730
0x4200100b - timer_interrupt::__xtensa_lx_rt_main
    at C:\projects\clean\esp-hal\examples\src\bin\timer_interrupt.rs:51
A0=0x820096dd       A1=0x3fcdc640       A2=0x00000100       A3=0x60023004       A4=0x00000001
A5=0x00000000       A6=0x20000000       A7=0x00000000       A8=0x3fcdc6a0       A9=0x00000000
A10=0x00060720      A11=0x00000000      A12=0x3fc898bc      A13=0x60038004      A14=0x40000000
A15=0x00000002
SAR=00000004
EXCCAUSE=0x00000020 EXCVADDR=0x00000000
LBEG=0x403cea32     LEND=0x403cea36     LCOUNT=0x00000000
THREADPTR=0x00000000
SCOMPARE1=0x00000100
BR=0x00000000
ACCLO=0x00000000    ACCHI=0x00000000
M0=0x00000000       M1=0x00000000       M2=0x00000000       M3=0x00000000
F64R_LO=0xb771a38d  F64R_HI=0xfda3967a  F64S=0xceabbb75
FCR=0xad079982      FSR=0xe9b6ceef
F0=0xb42c050c       F1=0xf3136273       F2=0xfdf79f6b       F3=0x2138d447       F4=0x3937a6fe
F5=0x3c76fd99       F6=0x73228270       F7=0xde1e6a95       F8=0x11e78072       F9=0xd4a13bb0
F10=0x4016858f      F11=0x3278441b      F12=0xc7feff6f      F13=0xfe4cf3ff      F14=0x08361538
F15=0xff8a7623
0x40378da1
ESP32Reset
    at ??:??

So apparently after running the ISR Cp0 is still disabled.

[bjoernQ]

Closed via #2057