Re: [PATCH 9/9] gpu: nova-core: gsp: add CeGetFaultMethodBufferSize RM control command

[Joel Fernandes <joelagnelf@nvidia.com>]

On Fri, Feb 27, 2026 at 09:32:14PM +0900, Eliot Courtney wrote:
> Add `CeGetFaultMethodBufferSizeParams` which wraps the bindings.
> 
> Add `get_ce_fault_method_buffer_size` which sends the RM control RPC
> and returns the buffer size. This is needed for channel allocation.
> 
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
> ---
>  drivers/gpu/nova-core/gsp/fw/rm.rs       | 17 +++++++++++++++
>  drivers/gpu/nova-core/gsp/rm/commands.rs | 36 +++++++++++++++++++++++++++++---
>  2 files changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/nova-core/gsp/fw/rm.rs b/drivers/gpu/nova-core/gsp/fw/rm.rs
> index 8bb7b11736b9..9f1e3546d39d 100644
> --- a/drivers/gpu/nova-core/gsp/fw/rm.rs
> +++ b/drivers/gpu/nova-core/gsp/fw/rm.rs
> @@ -80,3 +80,20 @@ unsafe impl FromBytes for GspRmControl {}
>  
>  // SAFETY: This struct contains no padding.
>  unsafe impl AsBytes for GspRmControl {}
> +
> +/// Wrapper for [`bindings::NV2080_CTRL_CE_GET_FAULT_METHOD_BUFFER_SIZE_PARAMS`].
> +#[derive(Zeroable)]

nit: This patch is not using zeroed(), so do you really need Zeroable here?
Also check other patches where you might have added this trait but not used it.

Other than this nit,
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>

thanks,

--
Joel Fernandes






> +#[repr(transparent)]
> +pub(crate) struct CeGetFaultMethodBufferSizeParams(
> +    bindings::NV2080_CTRL_CE_GET_FAULT_METHOD_BUFFER_SIZE_PARAMS,
> +);
> +
> +impl CeGetFaultMethodBufferSizeParams {
> +    /// Returns the CE fault method buffer size in bytes.
> +    pub(crate) fn size(&self) -> u32 {
> +        self.0.size
> +    }
> +}
> +
> +// SAFETY: This struct only contains integer types for which all bit patterns are valid.
> +unsafe impl FromBytes for CeGetFaultMethodBufferSizeParams {}
> diff --git a/drivers/gpu/nova-core/gsp/rm/commands.rs b/drivers/gpu/nova-core/gsp/rm/commands.rs
> index 16bcf88644db..1d045e6f1afb 100644
> --- a/drivers/gpu/nova-core/gsp/rm/commands.rs
> +++ b/drivers/gpu/nova-core/gsp/rm/commands.rs
> @@ -2,10 +2,14 @@
>  
>  use core::{
>      array,
> -    convert::Infallible, //
> +    convert::Infallible,
> +    mem::size_of, //
>  };
>  
> -use kernel::prelude::*;
> +use kernel::{
> +    prelude::*,
> +    transmute::FromBytes, //
> +};
>  
>  use crate::{
>      driver::Bar0,
> @@ -94,7 +98,6 @@ fn read(
>  }
>  
>  /// Sends an RM control command, checks the reply status, and returns the raw parameter bytes.
> -#[expect(dead_code)]
>  fn send_rm_control(
>      cmdq: &Cmdq,
>      bar: &Bar0,
> @@ -109,3 +112,30 @@ fn send_rm_control(
>  
>      Ok(reply.params)
>  }
> +
> +/// Sends the `CeGetFaultMethodBufferSize` RM control command and waits for its reply.
> +///
> +/// Returns the CE fault method buffer size in bytes.
> +#[expect(dead_code)]
> +pub(crate) fn get_ce_fault_method_buffer_size(
> +    cmdq: &Cmdq,
> +    bar: &Bar0,
> +    h_client: u32,
> +    h_subdevice: u32,
> +) -> Result<u32> {
> +    // Stack-allocate the request; CeGetFaultMethodBufferSizeParams is small (4 bytes).
> +    let req = [0u8; size_of::<CeGetFaultMethodBufferSizeParams>()];
> +
> +    let reply = send_rm_control(
> +        cmdq,
> +        bar,
> +        h_client,
> +        h_subdevice,
> +        RmControlMsgFunction::CeGetFaultMethodBufferSize,
> +        &req,
> +    )?;
> +
> +    let params = CeGetFaultMethodBufferSizeParams::from_bytes(&reply).ok_or(EINVAL)?;
> +
> +    Ok(params.size())
> +}
> 
> -- 
> 2.53.0
>