Re: [PATCH v2 0/9] gpu: nova-core: gsp: add continuation record support

[Zhi Wang]

On Thu, 19 Feb 2026 16:30:49 +0900
Eliot Courtney <ecourtney@xxxxxxxxxx> wrote:

Tested-by: Zhi Wang <zhiw@xxxxxxxxxx>

> GSP commands over 16 pages need to be sent using "continuation
> records" which essentially means splitting the payload over multiple
> commands.
> 
> This series adds a command type `ContinuationRecord` which just writes
> its header and whatever payload it is given. It also adds types
> `SplitState` and `SplitCommand` which support splitting a large RPC
> into smaller ones while transparently letting regular sized RPCs be
> sent without extra copies.
> 
> The send pathway uses `SplitState` to send all commands, but if
> the command fits into 16 pages, it still writes directly into the
> command queue. If it is larger than 16 pages and needs continuation
> records, it writes into a staging buffer, so there is one copy.
> 
> Signed-off-by: Eliot Courtney <ecourtney@xxxxxxxxxx>
> ---
> Changes in v2:
> - Added doccoments
> - Renamed driver_bytes_available_to_write to driver_write_area_size
> - allocate_command_with_timeout merged allocate_command with timeout
> parameter
> - Replaced hardcoded GSP_PAGE_SIZE * 16 with bindings
> - Changed oversized command error from EIO to EMSGSIZE
> - Added EMSGSIZE to kernel/error.rs
> - Split WrappingCommand functionality into SplitState + SplitCommand
> enum
> - Made max_size a const (MAX_CMD_SIZE)
> - Removed send_continuation_record + added comment for type inference
> - send_single_command now consumes the command
> - Extracted command_size + used in SplitState 
> - Link to v1:
> https://lore.kernel.org/r/20260212-cmdq-continuation-v1-0-73079ded55e6@xxxxxxxxxx
> 
> ---
> Eliot Courtney (9):
>       gpu: nova-core: gsp: sort MsgFunction variants alphabetically
>       gpu: nova-core: gsp: add mechanism to wait for space on command
> queue rust: add EMSGSIZE error code
>       gpu: nova-core: gsp: add checking oversized commands
>       gpu: nova-core: gsp: clarify invariant on command queue
>       gpu: nova-core: gsp: unconditionally call variable payload
> handling gpu: nova-core: gsp: add command_size helper
>       gpu: nova-core: gsp: support large RPCs via continuation record
>       gpu: nova-core: gsp: add tests for SplitState
> 
>  drivers/gpu/nova-core/gsp/cmdq.rs                 | 118 +++++++---
>  drivers/gpu/nova-core/gsp/commands.rs             | 256
> +++++++++++++++++++++- drivers/gpu/nova-core/gsp/fw.rs
>    | 106 +++++---- drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
> |   1 + rust/kernel/error.rs                              |   1 +
>  5 files changed, 408 insertions(+), 74 deletions(-)
> ---
> base-commit: 956b9cbd7f156c8672dac94a00de3c6a0939c692
> change-id: 20260203-cmdq-continuation-b99f3d5966c3
> 
> Best regards,