rust: dma: update to keyworded index projection syntax

Demonstrate the preferred syntax of index projection in DMA documentation
and examples. A few `[i]?` cases are converted to demonstrate the new
variant.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260602-projection-syntax-rework-v2-4-6989470f5440@garyguo.net
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 5 insertions, 7 deletions

diff --git a/samples/rust/rust_dma.rs b/samples/rust/rust_dma.rs
index 129bb4b39c04..a2c34bb74273 100644
--- a/samples/rust/rust_dma.rs
+++ b/samples/rust/rust_dma.rs
@@ -73,7 +73,7 @@ impl pci::Driver for DmaSampleDriver {
                 Coherent::zeroed_slice(pdev.as_ref(), TEST_VALUES.len(), GFP_KERNEL)?;
 
             for (i, value) in TEST_VALUES.into_iter().enumerate() {
-                kernel::dma_write!(ca, [i]?, MyStruct::new(value.0, value.1));
+                kernel::dma_write!(ca, [try: i], MyStruct::new(value.0, value.1));
             }
 
             let size = 4 * page::PAGE_SIZE;
@@ -91,16 +91,14 @@ impl pci::Driver for DmaSampleDriver {
 }
 
 impl DmaSampleDriver {
-    fn check_dma(&self) -> Result {
+    fn check_dma(&self) {
         for (i, value) in TEST_VALUES.into_iter().enumerate() {
-            let val0 = kernel::dma_read!(self.ca, [i]?.h);
-            let val1 = kernel::dma_read!(self.ca, [i]?.b);
+            let val0 = kernel::dma_read!(self.ca, [panic: i].h);
+            let val1 = kernel::dma_read!(self.ca, [panic: i].b);
 
             assert_eq!(val0, value.0);
             assert_eq!(val1, value.1);
         }
-
-        Ok(())
     }
 }
 
@@ -109,7 +107,7 @@ impl PinnedDrop for DmaSampleDriver {
     fn drop(self: Pin<&mut Self>) {
         dev_info!(self.pdev, "Unload DMA test driver.\n");
 
-        assert!(self.check_dma().is_ok());
+        self.check_dma();
 
         for (i, entry) in self.sgt.iter().enumerate() {
             dev_info!(