Re: [PATCH v6 4/8] rust: gem: Introduce DriverObject::Args

[Janne Grunau <j@jannau.net>]

On Tue, Dec 02, 2025 at 05:03:30PM -0500, Lyude Paul wrote:
> This is an associated type that may be used in order to specify a data-type
> to pass to gem objects when construction them, allowing for drivers to more
> easily initialize their private-data for gem objects.
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
> 
> ---
> V3:
> * s/BaseDriverObject/DriverObject/
> V4:
> * Fix leftover reference to BaseObjectDriver in rustdoc for
>   DriverObject::Args
> V6:
> * Fix build errors in Tyr
> 
>  drivers/gpu/drm/nova/gem.rs |  5 +++--
>  drivers/gpu/drm/tyr/gem.rs  |  3 ++-
>  rust/kernel/drm/gem/mod.rs  | 13 ++++++++++---
>  3 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nova/gem.rs b/drivers/gpu/drm/nova/gem.rs
> index 2760ba4f3450b..173077eeb2def 100644
> --- a/drivers/gpu/drm/nova/gem.rs
> +++ b/drivers/gpu/drm/nova/gem.rs
> @@ -18,8 +18,9 @@ pub(crate) struct NovaObject {}
>  
>  impl gem::DriverObject for NovaObject {
>      type Driver = NovaDriver;
> +    type Args = ();
>  
> -    fn new(_dev: &NovaDevice, _size: usize) -> impl PinInit<Self, Error> {
> +    fn new(_dev: &NovaDevice, _size: usize, _args: Self::Args) -> impl PinInit<Self, Error> {
>          try_pin_init!(NovaObject {})
>      }
>  }
> @@ -33,7 +34,7 @@ pub(crate) fn new(dev: &NovaDevice, size: usize) -> Result<ARef<gem::Object<Self
>              return Err(EINVAL);
>          }
>  
> -        gem::Object::new(dev, aligned_size)
> +        gem::Object::new(dev, aligned_size, ())
>      }
>  
>      /// Look up a GEM object handle for a `File` and return an `ObjectRef` for it.
> diff --git a/drivers/gpu/drm/tyr/gem.rs b/drivers/gpu/drm/tyr/gem.rs
> index 1273bf89dbd5d..bb5e7871efa94 100644
> --- a/drivers/gpu/drm/tyr/gem.rs
> +++ b/drivers/gpu/drm/tyr/gem.rs
> @@ -11,8 +11,9 @@ pub(crate) struct TyrObject {}
>  
>  impl gem::DriverObject for TyrObject {
>      type Driver = TyrDriver;
> +    type Args = ();
>  
> -    fn new(_dev: &TyrDevice, _size: usize) -> impl PinInit<Self, Error> {
> +    fn new(_dev: &TyrDevice, _size: usize, _args: ()) -> impl PinInit<Self, Error> {

nit: should the type for _args be Self::Args for consistency?

>          try_pin_init!(TyrObject {})
>      }
>  }
> diff --git a/rust/kernel/drm/gem/mod.rs b/rust/kernel/drm/gem/mod.rs
> index ec3c1b1775196..4bcaee2d4b308 100644
> --- a/rust/kernel/drm/gem/mod.rs
> +++ b/rust/kernel/drm/gem/mod.rs
> @@ -64,8 +64,15 @@ pub trait DriverObject: Sync + Send + Sized {
>      /// Parent `Driver` for this object.
>      type Driver: drm::Driver;
>  
> +    /// The data type to use for passing arguments to [`DriverObject::new`].
> +    type Args;
> +
>      /// Create a new driver data object for a GEM object of a given size.
> -    fn new(dev: &drm::Device<Self::Driver>, size: usize) -> impl PinInit<Self, Error>;
> +    fn new(
> +        dev: &drm::Device<Self::Driver>,
> +        size: usize,
> +        args: Self::Args,
> +    ) -> impl PinInit<Self, Error>;
>  
>      /// Open a new handle to an existing object, associated with a File.
>      fn open(_obj: &<Self::Driver as drm::Driver>::Object, _file: &DriverFile<Self>) -> Result {
> @@ -244,11 +251,11 @@ impl<T: DriverObject> Object<T> {
>      };
>  
>      /// Create a new GEM object.
> -    pub fn new(dev: &drm::Device<T::Driver>, size: usize) -> Result<ARef<Self>> {
> +    pub fn new(dev: &drm::Device<T::Driver>, size: usize, args: T::Args) -> Result<ARef<Self>> {
>          let obj: Pin<KBox<Self>> = KBox::pin_init(
>              try_pin_init!(Self {
>                  obj: Opaque::new(bindings::drm_gem_object::default()),
> -                data <- T::new(dev, size),
> +                data <- T::new(dev, size, args),
>              }),
>              GFP_KERNEL,
>          )?;
> -- 
> 2.52.0

Reviewed-by: Janne Grunau <j@jananu.net>

Janne