Clean up TX descriptors a little

Author: datdenkikniet

src/dma/raw_descriptor.rs

@@ -80,6 +80,10 @@ impl<'data, T> DescriptorRing<'data, T> {
         (&mut self.descriptors[index], &mut self.buffers[index])
     }
 
+    pub fn descriptors_mut(&mut self) -> impl Iterator<Item = &mut T> {
+        self.descriptors.iter_mut()
+    }
+
     pub fn descriptors(&self) -> impl Iterator<Item = &T> {
         self.descriptors.iter()
     }
@@ -100,10 +104,6 @@ impl<'data, T> DescriptorRing<'data, T> {
         &self.buffers[self.buffers.len() - 1]
     }
 
-    pub fn descriptors_mut(&mut self) -> impl Iterator<Item = &mut T> {
-        self.descriptors.iter_mut()
-    }
-
     pub fn descriptors_and_buffers(
         &mut self,
     ) -> impl Iterator<Item = (&mut T, &mut [u8; MTU + 2])> {

src/dma/tx/f_series_desc.rs

@@ -65,8 +65,9 @@ impl TxDescriptor {
         }
     }
 
-    pub(super) fn setup(&mut self, buffer: &mut [u8]) {
-        self.set_buffer(buffer);
+    pub(super) fn setup(&mut self) {
+        (0..crate::dma::raw_descriptor::DESC_SIZE)
+            .for_each(|i| unsafe { self.inner_raw.write(i, 0) });
     }
 
     #[allow(unused)]

src/dma/tx/h_desc.rs

@@ -149,10 +149,10 @@ impl TxDescriptor {
         (self.inner_raw.read(3) & TXDESC_3_LD) == TXDESC_3_LD
     }
 
-    // Placeholder for API parity with f-series descriptor.
-    pub(super) fn setup(&mut self, _: &[u8]) {
+    pub(super) fn setup(&mut self) {
         // Zero-out all fields in the descriptor
         (0..4).for_each(|n| unsafe { self.inner_raw.write(n, 0) });
+        self.packet_id.take();
     }
 
     pub(super) fn is_owned(&self) -> bool {

src/dma/tx/mod.rs

@@ -95,8 +95,8 @@ impl<'data> TxRing<'data, NotRunning> {
     /// Start the Tx DMA engine
     pub fn start(mut self, eth_dma: &ETHERNET_DMA) -> TxRing<'data, Running> {
         // Setup ring
-        for (descriptor, buffer) in self.ring.descriptors_and_buffers() {
-            descriptor.setup(buffer);
+        for descriptor in self.ring.descriptors_mut() {
+            descriptor.setup();
         }
 
         #[cfg(feature = "f-series")]
@@ -120,10 +120,7 @@ impl<'data> TxRing<'data, NotRunning> {
 
             // Assert that the descriptors are properly aligned.
             assert!(ring_ptr as u32 & !0b11 == ring_ptr as u32);
-            assert!(
-                self.ring.last_descriptor() as *const _ as u32 & !0b11
-                    == self.ring.last_descriptor() as *const _ as u32
-            );
+            assert!(self.ring.last_descriptor() as *const _ as u32 % 4 == 0);
 
             // Set the start pointer.
             eth_dma