Re: [PATCH 3/4] gpu: nova-core: gsp: cmdq: add the GMC send path

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] gpu: nova-core: return type mismatch in CmdqInner::send_gmc_command()
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commit 1e1d150084c3f6fc3d6e13ffe004caffa1b2a4a0
Author: John Hubbard <jhubbard@nvidia.com>

gpu: nova-core: gsp: cmdq: add the GMC send path

This commit adds the gmc submodule to the GSP command queue in nova-core to
support sending GPU Management Controller (GMC) API commands such as GSP_INIT.

> diff --git a/drivers/gpu/nova-core/gsp/cmdq/gmc.rs b/drivers/gpu/nova-core/gsp/cmdq/gmc.rs
> new file mode 100644
> index 0000000000000..b035f30479a84
> --- /dev/null
> +++ b/drivers/gpu/nova-core/gsp/cmdq/gmc.rs
> @@ -0,0 +1,194 @@
[ ... ]
> +impl CmdqInner<'_> {
> +    /// Sends `command` to the GSP, and returns the sequence number of its element.
> +    ///
> +    /// Unlike RPC commands, GMC commands are never split: a command that does not fit in a single
> +    /// element is an error.
> +    ///
> +    /// # Errors
> +    ///
> +    /// - `EMSGSIZE` if the command does not fit in a single command queue element.
> +    /// - `ETIMEDOUT` if space does not become available 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 initializer are propagated as-is.
> +    fn send_gmc_command<C>(&mut self, command: C) -> Result<u32>
> +    where
> +        C: CommandToGsp,
> +        Error: From<C::InitError>,
> +    {
> +        self.send_command_element(GmcCommandElement(command))
> +    }
> +}

[Severity: Low]
Does this compile when CONFIG_DRM_NOVA is enabled?

In drivers/gpu/nova-core/gsp/cmdq/gmc.rs, CmdqInner::send_gmc_command() is
declared with a return type of Result<u32> and directly returns the result of
self.send_command_element().

However, in drivers/gpu/nova-core/gsp/cmdq.rs, CmdqInner::send_command_element()
returns Result (i.e. Result<(), Error>):

    fn send_command_element<E: CommandElement>(&mut self, command: E) -> Result {
        ...
        Ok(())
    }

Wouldn't this fail to build with a mismatched types error?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103-r000_rebase_on_cmdq-rpc-v1-0-189f9ff3bfd2@nvidia.com?part=3