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

[Zhi Wang <zhiw@nvidia.com>]

On Tue, 18 Aug 2026 20:51:56 -0700
John Hubbard <jhubbard@nvidia.com> wrote:

One nit: might be better to update the doc as well.

Reviewed-by: Zhi Wang <zhiw@nvidia.com>

diff --git a/Documentation/gpu/nova/core/fsp.rst
b/Documentation/gpu/nova/core/fsp.rst index 52d618d22bb8..60c647181da0
100644 --- a/Documentation/gpu/nova/core/fsp.rst
+++ b/Documentation/gpu/nova/core/fsp.rst
@@ -106,6 +106,8 @@ All FSP messages share a common header format
consisting of two 32-bit words:
 - Bit 30: EOM (End of Message)
 - Bits 29:28: Packet sequence number
 - Bits 23:16: Source Endpoint ID
+- Bits 15:8: Destination Endpoint ID
+- Bits 3:0: MCTP header version (1)
 
 **NVDM header** (NVIDIA Vendor Defined Message):
 


> 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 <jhubbard@nvidia.com>
> ---
>  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`).