LailaTheElf/embassy
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SpiDevice cancel safety: always set CS pin to high on drop

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If a transfer is dropped, the CS will stay in a low state, which
seems to be unsafe.
This commit is contained in:
Shaw Drastin 2025-02-04 10:53:45 +08:00
parent 2c8a550410
commit 188828775e
2 changed files with 12 additions and 4 deletions
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1
embassy-embedded-hal/Cargo.toml
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@ -22,6 +22,7 @@ time = ["dep:embassy-time"]
default = ["time"] default = ["time"]
[dependencies] [dependencies]
embassy-hal-internal = { version = "0.2.0", path = "../embassy-hal-internal" }
embassy-futures = { version = "0.1.0", path = "../embassy-futures" } embassy-futures = { version = "0.1.0", path = "../embassy-futures" }
embassy-sync = { version = "0.6.2", path = "../embassy-sync" } embassy-sync = { version = "0.6.2", path = "../embassy-sync" }
embassy-time = { version = "0.4.0", path = "../embassy-time", optional = true } embassy-time = { version = "0.4.0", path = "../embassy-time", optional = true }

15
embassy-embedded-hal/src/shared_bus/asynch/spi.rs
View File

@ -25,6 +25,7 @@
//! let display2 = ST7735::new(spi_dev2, dc2, rst2, Default::default(), 160, 128); //! let display2 = ST7735::new(spi_dev2, dc2, rst2, Default::default(), 160, 128);
//! ``` //! ```
use embassy_hal_internal::drop::OnDrop;
use embassy_sync::blocking_mutex::raw::RawMutex; use embassy_sync::blocking_mutex::raw::RawMutex;
use embassy_sync::mutex::Mutex; use embassy_sync::mutex::Mutex;
use embedded_hal_1::digital::OutputPin; use embedded_hal_1::digital::OutputPin;
@ -70,6 +71,10 @@ where
let mut bus = self.bus.lock().await; let mut bus = self.bus.lock().await;
self.cs.set_low().map_err(SpiDeviceError::Cs)?; self.cs.set_low().map_err(SpiDeviceError::Cs)?;
let cs_drop = OnDrop::new(|| {
let _ = self.cs.set_high();
});
let op_res = 'ops: { let op_res = 'ops: {
for op in operations { for op in operations {
let res = match op { let res = match op {
@ -97,11 +102,10 @@ where
// On failure, it's important to still flush and deassert CS. // On failure, it's important to still flush and deassert CS.
let flush_res = bus.flush().await; let flush_res = bus.flush().await;
let cs_res = self.cs.set_high(); drop(cs_drop);
let op_res = op_res.map_err(SpiDeviceError::Spi)?; let op_res = op_res.map_err(SpiDeviceError::Spi)?;
flush_res.map_err(SpiDeviceError::Spi)?; flush_res.map_err(SpiDeviceError::Spi)?;
cs_res.map_err(SpiDeviceError::Cs)?;
Ok(op_res) Ok(op_res)
} }
@ -155,6 +159,10 @@ where
bus.set_config(&self.config).map_err(|_| SpiDeviceError::Config)?; bus.set_config(&self.config).map_err(|_| SpiDeviceError::Config)?;
self.cs.set_low().map_err(SpiDeviceError::Cs)?; self.cs.set_low().map_err(SpiDeviceError::Cs)?;
let cs_drop = OnDrop::new(|| {
let _ = self.cs.set_high();
});
let op_res = 'ops: { let op_res = 'ops: {
for op in operations { for op in operations {
let res = match op { let res = match op {
@ -182,11 +190,10 @@ where
// On failure, it's important to still flush and deassert CS. // On failure, it's important to still flush and deassert CS.
let flush_res = bus.flush().await; let flush_res = bus.flush().await;
let cs_res = self.cs.set_high(); drop(cs_drop);
let op_res = op_res.map_err(SpiDeviceError::Spi)?; let op_res = op_res.map_err(SpiDeviceError::Spi)?;
flush_res.map_err(SpiDeviceError::Spi)?; flush_res.map_err(SpiDeviceError::Spi)?;
cs_res.map_err(SpiDeviceError::Cs)?;
Ok(op_res) Ok(op_res)
} }