From c37054495083b28d6cf1a9b93fbd96625a71f16d Mon Sep 17 00:00:00 2001
From: Trey Aspelund <trey@oxidecomputer.com>
Date: Tue, 10 Nov 2026 15:21:54 -0500
Subject: [PATCH] dpd: parse xcvr_defaults.rs without snake_case

Use the older version of the PortFec type when parsing xcvr_defaults.csv
then convert to the newer type. This allows us to parse old versions of
the file without needing any producers of the file to update them.

Signed-off-by: Trey Aspelund <trey@oxidecomputer.com>
---
 dpd/src/switch_port.rs | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/dpd/src/switch_port.rs b/dpd/src/switch_port.rs
index 9ba24091..d8604e0e 100644
--- a/dpd/src/switch_port.rs
+++ b/dpd/src/switch_port.rs
@@ -31,6 +31,7 @@ use common::ports::QsfpPort;
 use common::ports::RearPort;
 use common::ports::TxEq;
 use common::ports::XcvrSettings;
+use dpd_types_versions::v1;
 use std::collections::BTreeMap;
 
 /// Return the backplane link information, if this is a rear port.
@@ -54,8 +55,9 @@ pub fn module_id_from_qsfp(p: QsfpPort) -> transceiver_controller::ModuleId {
 struct XcvrDefaultsEntry {
     /// Manufacturer part number - unique identifer for a transceiver
     pub mpn: String,
-    /// FEC
-    pub fec: Option<PortFec>,
+    /// FEC. For stability, the on-disk format is parsed with the v1
+    /// `PortFec` representation.
+    pub fec: Option<v1::port::PortFec>,
     /// Precursor 2
     pub pre2: Option<i32>,
     /// Precursor 1
@@ -99,7 +101,8 @@ pub fn load_xcvr_defaults(
         } else {
             None
         };
-        settings.insert(e.mpn, XcvrSettings { tx_eq, fec: e.fec });
+        settings
+            .insert(e.mpn, XcvrSettings { tx_eq, fec: e.fec.map(Into::into) });
     }
     Ok(settings)
 }
@@ -525,3 +528,21 @@ impl crate::Switch {
         Err(DpdError::NoTransceiverController)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::load_xcvr_defaults;
+    use common::ports::PortFec;
+
+    // The shipped defaults file must keep parsing even as the API's
+    // `PortFec` serialization changes.
+    #[test]
+    fn shipped_xcvr_defaults_parse() {
+        let path =
+            concat!(env!("CARGO_MANIFEST_DIR"), "/misc/xcvr_defaults.csv");
+        let settings = load_xcvr_defaults(path).unwrap();
+        assert_eq!(settings["OXIDESOFTNPU"].fec, Some(PortFec::RS));
+        assert_eq!(settings["CAB-Q-Q-5M"].fec, Some(PortFec::None));
+        assert_eq!(settings["FTLC9558REPM"].fec, None);
+    }
+}