[PATCH 03/27] gpu: nova-core: set MCTP transport header version to 1

FSP requires MCTP transport header version 1. Nova-core leaves version
bits 3:0 at zero, so every CoT and PRC request carries an invalid
transport header.

Define the version and destination endpoint ID fields. Set the version
to 1 for single-packet requests, and leave the unused destination
endpoint ID at zero.

Assisted-by: Cursor:claude-opus-5
Signed-off-by: John Hubbard <[email protected]>
---
 drivers/gpu/nova-core/mctp.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nova-core/mctp.rs b/drivers/gpu/nova-core/mctp.rs
index 90c642c91a72..03546213da28 100644
--- a/drivers/gpu/nova-core/mctp.rs
+++ b/drivers/gpu/nova-core/mctp.rs
@@ -42,13 +42,23 @@ pub(crate) struct MctpHeader(u32) {
         29:28 seq;
         /// Source endpoint ID.
         23:16 seid;
+        /// Destination endpoint ID.
+        15:8 deid;
+        /// MCTP header version.
+        3:0 version;
     }
 }
 
 impl MctpHeader {
-    /// Builds a single-packet MCTP header (`SOM=1`, `EOM=1`, `SEQ=0`, `SEID=0`).
+    /// MCTP specification version 1.0.
+    const VERSION: u32 = 1;
+
+    /// Builds a single-packet MCTP header (`SOM=1`, `EOM=1`, `SEQ=0`, `SEID=0`, `VERSION=1`).
     pub(crate) fn single_packet() -> Self {
-        Self::zeroed().with_som(true).with_eom(true)
+        Self::zeroed()
+            .with_const_version::<{ Self::VERSION }>()
+            .with_som(true)
+            .with_eom(true)
     }
 
     /// Returns whether this is a complete single-packet message (`SOM=1` and `EOM=1`).
-- 
2.55.0