From 466dcc2a150c1d0b87a78506b3def8ea46a96b09 Mon Sep 17 00:00:00 2001
From: Robin Mueller <31589589+robamu@users.noreply.github.com>
Date: Mon, 19 May 2025 10:49:41 +0200
Subject: [PATCH] allow stealing the RMT channel creator + Drop bugfix (#3496)

---
 esp-hal/CHANGELOG.md |  2 ++
 esp-hal/src/rmt.rs   | 69 ++++++++++++++++++++------------------------
 2 files changed, 33 insertions(+), 38 deletions(-)

diff --git a/esp-hal/CHANGELOG.md b/esp-hal/CHANGELOG.md
index d48c73958..719585ef4 100644
--- a/esp-hal/CHANGELOG.md
+++ b/esp-hal/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- RMT channel creator `steal` function (#3496)
 - Support for RMT extended memory (#3182)
 - Support for `rand_core` 0.9 (#3211)
 - `ESP_HAL_CONFIG_STACK_GUARD_OFFSET` and `ESP_HAL_CONFIG_STACK_GUARD_VALUE` to configure Rust's [Stack smashing protection](https://doc.rust-lang.org/rustc/exploit-mitigations.html#stack-smashing-protection) (#3203)
@@ -65,6 +66,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- RMT channel drop implementation bugfix where the channel was not released properly (#3496)
 - RMT now uses correct max filter threshold of 255 instead of 127 (#3192)
 - Full-duplex SPI works when mixed with half-duplex SPI (#3176)
 - `Uart::flush_async` should no longer return prematurely (#3186)
diff --git a/esp-hal/src/rmt.rs b/esp-hal/src/rmt.rs
index 1a5d393fd..6836b12ca 100644
--- a/esp-hal/src/rmt.rs
+++ b/esp-hal/src/rmt.rs
@@ -401,7 +401,7 @@ impl Default for RxChannelConfig {
     }
 }
 
-pub use impl_for_chip::{ChannelCreator, Rmt};
+pub use impl_for_chip::Rmt;
 
 impl<'d, Dm> Rmt<'d, Dm>
 where
@@ -781,10 +781,35 @@ macro_rules! impl_rx_channel_creator {
     };
 }
 
+/// RMT Channel Creator
+pub struct ChannelCreator<Dm, const CHANNEL: u8>
+where
+    Dm: crate::DriverMode,
+{
+    phantom: PhantomData<Dm>,
+    _guard: GenericPeripheralGuard<{ crate::system::Peripheral::Rmt as u8 }>,
+}
+
+impl<Dm: crate::DriverMode, const CHANNEL: u8> ChannelCreator<Dm, CHANNEL> {
+    /// Unsafely steal a channel creator instance.
+    ///
+    /// # Safety
+    ///
+    /// Circumvents HAL ownership and safety guarantees and allows creating
+    /// multiple handles to the same peripheral structure.
+    pub unsafe fn steal() -> ChannelCreator<Dm, CHANNEL> {
+        ChannelCreator {
+            phantom: PhantomData,
+            _guard: GenericPeripheralGuard::new(),
+        }
+    }
+}
+
 #[cfg(not(any(esp32, esp32s2, esp32s3)))]
 mod impl_for_chip {
     use core::marker::PhantomData;
 
+    use super::ChannelCreator;
     use crate::system::GenericPeripheralGuard;
 
     /// RMT Instance
@@ -832,15 +857,6 @@ mod impl_for_chip {
         }
     }
 
-    /// RMT Channel Creator
-    pub struct ChannelCreator<Dm, const CHANNEL: u8>
-    where
-        Dm: crate::DriverMode,
-    {
-        phantom: PhantomData<Dm>,
-        _guard: GenericPeripheralGuard<{ crate::system::Peripheral::Rmt as u8 }>,
-    }
-
     impl_tx_channel_creator!(0);
     impl_tx_channel_creator!(1);
 
@@ -858,6 +874,7 @@ mod impl_for_chip {
 mod impl_for_chip {
     use core::marker::PhantomData;
 
+    use super::ChannelCreator;
     use crate::{peripherals::RMT, system::GenericPeripheralGuard};
 
     /// RMT Instance
@@ -929,15 +946,6 @@ mod impl_for_chip {
         }
     }
 
-    /// RMT Channel Creator
-    pub struct ChannelCreator<Dm, const CHANNEL: u8>
-    where
-        Dm: crate::DriverMode,
-    {
-        phantom: PhantomData<Dm>,
-        _guard: GenericPeripheralGuard<{ crate::system::Peripheral::Rmt as u8 }>,
-    }
-
     impl_tx_channel_creator!(0);
     impl_tx_channel_creator!(1);
     impl_tx_channel_creator!(2);
@@ -979,6 +987,7 @@ mod impl_for_chip {
 mod impl_for_chip {
     use core::marker::PhantomData;
 
+    use super::ChannelCreator;
     use crate::{peripherals::RMT, system::GenericPeripheralGuard};
 
     /// RMT Instance
@@ -1026,15 +1035,6 @@ mod impl_for_chip {
         }
     }
 
-    /// RMT Channel Creator
-    pub struct ChannelCreator<Dm, const CHANNEL: u8>
-    where
-        Dm: crate::DriverMode,
-    {
-        phantom: PhantomData<Dm>,
-        _guard: GenericPeripheralGuard<{ crate::system::Peripheral::Rmt as u8 }>,
-    }
-
     impl_tx_channel_creator!(0);
     impl_tx_channel_creator!(1);
     impl_tx_channel_creator!(2);
@@ -1060,6 +1060,7 @@ mod impl_for_chip {
 mod impl_for_chip {
     use core::marker::PhantomData;
 
+    use super::ChannelCreator;
     use crate::{peripherals::RMT, system::GenericPeripheralGuard};
 
     /// RMT Instance
@@ -1131,15 +1132,6 @@ mod impl_for_chip {
         }
     }
 
-    /// RMT Channel Creator
-    pub struct ChannelCreator<Dm, const CHANNEL: u8>
-    where
-        Dm: crate::DriverMode,
-    {
-        phantom: PhantomData<Dm>,
-        _guard: GenericPeripheralGuard<{ crate::system::Peripheral::Rmt as u8 }>,
-    }
-
     impl_tx_channel_creator!(0);
     impl_tx_channel_creator!(1);
     impl_tx_channel_creator!(2);
@@ -1177,11 +1169,12 @@ where
     Dm: crate::DriverMode,
 {
     fn drop(&mut self) {
+        let memsize = chip_specific::channel_mem_size(CHANNEL);
+
         // This isn't really necessary, but be extra sure that this channel can't
         // interfere with others.
         chip_specific::set_channel_mem_size(CHANNEL, 0);
 
-        let memsize = chip_specific::channel_mem_size(CHANNEL);
         for s in STATE[usize::from(CHANNEL)..usize::from(CHANNEL + memsize)]
             .iter()
             .rev()