Re: [PATCH 00/10] gpu: nova-core: gsp: prepare the command queue for r000 dual-message types

[Alexandre Courbot]

On Sun Sep 27, 2026 at 8:14 PM JST, Alexandre Courbot wrote:
> The upcoming r000 firmware support [1] introduces a new type of command
> named GMC alongside the existing and already supported RPC command type.
>
> Since RPC was the only command type supported so far, it was embedded
> into the lowest command queue level: the message header actually
> includes the RPC header and the code considers them as one.
>
> This makes the r000/GMC support difficult to land without a refactor,
> with the result of transport layer code being duplicated between the two
> message types, and no clear separation between the RPC and GMC code
> which are mixed together in the command queue. Merging the code that way
> would introduce quite some technical debt.
>
> Thus, this series prepares a proper landing ground for a new message
> type by extracting all the RPC layer code and moving it into its own
> sub-modules, making the `cmdq` module completely agnostic of the type of
> message it transports. By the end of the series, the only mention of RPC
> in `cmdq.rs` is for the `rpc` sub-module.
>
> With the transport and message layers properly separated, support for
> GMC can be added into sibling modules of `rpc`, and the transport layer
> can be converted once when doing the switch to r000.
>
> This moves quite a bit of code around, but most of it is moved verbatim.
> No significant functional change is intended.
>
> For the r000 series, this essentially means the following:
>
> - Its patch 7 making `allocate_command` generic can be dropped as the
>   transport layer makes no assumption about the message type.
> - Patches adding GMC support will do it in dedicated `gmc` sub-modules,
>   following the model set by RPC. These `gmc` sub-modules will start as
>   `dead_code` as they are being built.
> - The "switch to r000" patch will essentially operate on the transport
>   layer level, i.e. `cmdq.rs`.
> - There should be no need for extra post-switch RPC fixing, as the
>   transport layer code will already be shared with GMC.
>
> Overall, this should make the r000 series much easier to review and
> eventually land, while not creating new technical debt.
>
> This series is based on `drm-rust-next`.

Sashiko has found a couple of serious issues, and I've found another I
had overlooked, so please ignore this revision. I will send v2 shortly.