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Merge #958

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958: Implement proper `Drop` for `BufferedUarte` r=lulf a=ZoeyR

The drop method in `BufferedUarte` was prone to hanging indefinitely and also didn't actually disable the peripheral. I mostly copied over the drop method from `Uarte` with some modifications since `BufferedUarte` could have a transmit lasting indefinitely.

Co-authored-by: Zoey Riordan <zoey@dos.cafe>
This commit is contained in:
bors[bot] 2022-09-23 11:58:43 +00:00 committed by GitHub
commit eeb1515e9f
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1 changed files with 17 additions and 25 deletions
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42
embassy-nrf/src/buffered_uarte.rs
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@ -26,7 +26,7 @@ use embassy_sync::waitqueue::WakerRegistration;
// Re-export SVD variants to allow user to directly set values // Re-export SVD variants to allow user to directly set values
pub use pac::uarte0::{baudrate::BAUDRATE_A as Baudrate, config::PARITY_A as Parity}; pub use pac::uarte0::{baudrate::BAUDRATE_A as Baudrate, config::PARITY_A as Parity};
use crate::gpio::Pin as GpioPin; use crate::gpio::{self, Pin as GpioPin};
use crate::interrupt::InterruptExt; use crate::interrupt::InterruptExt;
use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task}; use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task};
use crate::timer::{Frequency, Instance as TimerInstance, Timer}; use crate::timer::{Frequency, Instance as TimerInstance, Timer};
@ -428,21 +428,23 @@ impl<'a, U: UarteInstance, T: TimerInstance> Drop for StateInner<'a, U, T> {
fn drop(&mut self) { fn drop(&mut self) {
let r = U::regs(); let r = U::regs();
// TODO this probably deadlocks. do like Uarte instead.
self.timer.stop(); self.timer.stop();
if let RxState::Receiving = self.rx_state {
r.tasks_stoprx.write(|w| unsafe { w.bits(1) }); r.inten.reset();
} r.events_rxto.reset();
if let TxState::Transmitting(_) = self.tx_state { r.tasks_stoprx.write(|w| unsafe { w.bits(1) });
r.tasks_stoptx.write(|w| unsafe { w.bits(1) }); r.events_txstopped.reset();
} r.tasks_stoptx.write(|w| unsafe { w.bits(1) });
if let RxState::Receiving = self.rx_state {
low_power_wait_until(|| r.events_endrx.read().bits() == 1); while r.events_txstopped.read().bits() == 0 {}
} while r.events_rxto.read().bits() == 0 {}
if let TxState::Transmitting(_) = self.tx_state {
low_power_wait_until(|| r.events_endtx.read().bits() == 1); r.enable.write(|w| w.enable().disabled());
}
gpio::deconfigure_pin(r.psel.rxd.read().bits());
gpio::deconfigure_pin(r.psel.txd.read().bits());
gpio::deconfigure_pin(r.psel.rts.read().bits());
gpio::deconfigure_pin(r.psel.cts.read().bits());
} }
} }
@ -548,13 +550,3 @@ impl<'a, U: UarteInstance, T: TimerInstance> PeripheralState for StateInner<'a,
trace!("irq: end"); trace!("irq: end");
} }
} }
/// Low power blocking wait loop using WFE/SEV.
fn low_power_wait_until(mut condition: impl FnMut() -> bool) {
while !condition() {
// WFE might "eat" an event that would have otherwise woken the executor.
cortex_m::asm::wfe();
}
// Retrigger an event to be transparent to the executor.
cortex_m::asm::sev();
}