Re: [PATCH v2 3/4] nova-core: bitstruct: Add support for custom visiblity

Alexandre Courbot
2025-09-08T03:40:23Z

On Thu Sep 4, 2025 at 6:54 AM JST, Joel Fernandes wrote:
> Add support for custom visiblity to allow for users to control visibility
> of the structure and helpers.
>
> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
> ---
> drivers/gpu/nova-core/bitstruct.rs | 46 ++++++++++++++--------------
> drivers/gpu/nova-core/regs/macros.rs | 16 +++++-----
> 2 files changed, 31 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/nova-core/bitstruct.rs b/drivers/gpu/nova-core/bitstruct.rs
> index 068334c86981..1047c5c17e2d 100644
> --- a/drivers/gpu/nova-core/bitstruct.rs
> +++ b/drivers/gpu/nova-core/bitstruct.rs
> @@ -9,7 +9,7 @@
> ///
> /// ```rust
> /// bitstruct! {
> -/// struct ControlReg: u32 {
> +/// pub struct ControlReg: u32 {
> /// 3:0 mode as u8 ?=> Mode;
> /// 7:4 state as u8 => State;
> /// }

Maybe mention in the documentation that the field accessors are given
the same visibility as the type - otherwise one might be led into
thinking that they can specify visibility for individual fields as well
(I'm wondering whether we might ever want that in the future?).

> @@ -34,21 +34,21 @@
> /// and returns the result. This is useful with fields for which not all values are valid.
> macro_rules! bitstruct {
> // Main entry point - defines the bitfield struct with fields
> - (struct $name:ident : $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
> - bitstruct!(@core $name $storage $(, $comment)? { $($fields)* });
> + ($vis:vis struct $name:ident : $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
> + bitstruct!(@core $name $vis $storage $(, $comment)? { $($fields)* });
> };
>
> // All rules below are helpers.
>
> // Defines the wrapper `$name` type, as well as its relevant implementations (`Debug`,
> // `Default`, `BitOr`, and conversion to the value type) and field accessor methods.
> - (@core $name:ident $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {
> + (@core $name:ident $vis:vis $storage:ty $(, $comment:literal)? { $($fields:tt)* }) => {

Being very nitpicky here, but for consistency why not put `$vis` before
`$name` since it is the order they are given by the caller?

> $(
> #[doc=$comment]
> )?
> #[repr(transparent)]
> #[derive(Clone, Copy)]
> - pub(crate) struct $name($storage);
> + $vis struct $name($vis $storage);

`$storage` should probably be kept private - we already have accessors
for it, and the visibility parameter is for the outer type, not its
internals.