Re: [PATCH v3 3/5] gpu: nova-core: gsp: add reply/no-reply info to `CommandToGsp`

["Eliot Courtney" <ecourtney@nvidia.com>]

On Wed Mar 4, 2026 at 8:56 PM JST, Alexandre Courbot wrote:
>> +    /// Sends `command` to the GSP and waits for the reply.
>> +    ///
>> +    /// # Errors
>> +    ///
>> +    /// - `ETIMEDOUT` if space does not become available to send the command, or if the reply is
>> +    ///   not received within the timeout.
>> +    /// - `EIO` if the variable payload requested by the command has not been entirely
>> +    ///   written to by its [`CommandToGsp::init_variable_payload`] method.
>> +    ///
>> +    /// Error codes returned by the command and reply initializers are propagated as-is.
>> +    pub(crate) fn send_command<M>(&mut self, bar: &Bar0, command: M) -> Result<M::Reply>
>> +    where
>> +        M: CommandToGsp,
>> +        M::Reply: MessageFromGsp,
>> +        Error: From<M::InitError>,
>> +        Error: From<<M::Reply as MessageFromGsp>::InitError>,
>> +    {
>> +        self.send_command_internal(bar, command)?;
>> +
>> +        loop {
>> +            match self.receive_msg::<M::Reply>(Self::RECEIVE_TIMEOUT) {
>> +                Ok(reply) => break Ok(reply),
>> +                Err(ERANGE) => continue,
>> +                Err(e) => break Err(e),
>> +            }
>> +        }
>
> There is an opportunity for factorize some more code here.
>
> Notice how the other callers of `receive_msg` (`wait_gsp_init_done` and
> `GspSequencer::run`) both use the same kind of loop, down to the same
> error handling. We could move that loop logic here and do it in a single
> place.
>
> In the future, we will probably want to add handlers for
> unexpected messages from the GSP and it will be easier if we receive all
> messages from a single place.
>
> This can be a separate patch from this one, but I think it makes sense
> to have that in this series.
>
> I expect the last patch to change a bit as a consequence of that - maybe
> we will need a `receive_msg_loop` or something in `CmdqInner`.

I agree we should migrate all callers and make Cmdq responsible for
draining / handling spontaneous messages from the GSP, but I was
planning on doing it in a separate patch series until now. I can put it
into this one though if you want though no worries.