Re: [PATCH 3/4] gpu: nova-core: gsp: cmdq: ring the GSP doorbell from the queue memory

[Eliot Courtney]

On Fri Oct 30, 2026 at 4:41 PM JST, Alexandre Courbot wrote:
> From: John Hubbard <jhubbard@xxxxxxxxxx>
>
> A command reaches GSP-RM in two steps. The driver advances the command
> queue's write pointer, which publishes the command, and then writes
> NV_PGSP_QUEUE_HEAD, which interrupts the GSP so that it reads the queue.
> In msgq v0, the write pointer is in the queue's shared-memory header, so
> the two steps are two writes. In msgq v2, the write pointer is
> NV_PGSP_QUEUE_HEAD itself, so one register write does both.
>
> Nova-core split the two steps across two types. The queue memory type
> advanced the write pointer in shared memory, and the command queue type
> then rang the doorbell through a BAR0 mapping that it held for that one
> purpose.
>
> Move the BAR0 mapping into the queue memory type, and ring the doorbell
> at the end of the operation that advances the write pointer in order to
> prepare for the switch to msgq v2.
>
> No functional change intended.
>
> [ acourbot: slightly reword and trim commit message. ]
>
> Assisted-by: LLM
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
> ---

Reviewed-by: Eliot Courtney <ecourtney@xxxxxxxxxx>