Re: [PATCH 06/12] drm/tyr: add shmem backing for GEM objects

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 11 Feb 2026 17:37:07 -0800
Deborah Brouwer <deborah.brouwer@collabora.com> wrote:

> Add support for GEM buffer objects backed by shared memory.
> 
> This introduces the BoCreateArgs structure for passing creation parameters
> including flags, and adds a flags field to BoData. A new_dummy_object()
> helper is provided to create a dummy GEM object for use as a GPUVM root.
> 
> The Bo type alias is added to simplify working with Tyr's shmem-backed
> GEM objects throughout the driver.
> 
> Co-developed-by: Boris Brezillon <boris.brezillon@collabora.com>
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
> ---
>  drivers/gpu/drm/tyr/gem.rs | 52 ++++++++++++++++++++++++++++++++------
>  1 file changed, 44 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tyr/gem.rs b/drivers/gpu/drm/tyr/gem.rs
> index c1208d332dea..6a58f2da88d3 100644
> --- a/drivers/gpu/drm/tyr/gem.rs
> +++ b/drivers/gpu/drm/tyr/gem.rs
> @@ -1,28 +1,64 @@
>  // SPDX-License-Identifier: GPL-2.0 or MIT
> +//! GEM buffer object management for the Tyr driver.
> +//!
> +//! This module provides buffer object (BO) management functionality using
> +//! DRM's GEM subsystem with shmem backing.
>  
>  use kernel::{
>      drm::{
>          gem,
> +        gem::shmem,
>          DeviceContext, //
>      },
> -    prelude::*, //
> +    prelude::*,
> +    sync::aref::ARef, //
>  };
>  
> -use crate::driver::TyrDrmDriver;
> +use crate::driver::{
> +    TyrDrmDevice,
> +    TyrDrmDriver, //
> +};
>  
> -/// GEM Object inner driver data
> +/// Tyr's DriverObject type for GEM objects.
>  #[pin_data]
> -pub(crate) struct BoData {}
> +pub(crate) struct BoData {
> +    flags: u32,
> +}
> +
> +/// Provides a way to pass arguments when creating BoData
> +/// as required by the gem::DriverObject trait.
> +pub(crate) struct BoCreateArgs {
> +    flags: u32,
> +}
>  
>  impl gem::DriverObject for BoData {
>      type Driver = TyrDrmDriver;
> -    type Args = ();
> +    type Args = BoCreateArgs;
>  
>      fn new<Ctx: DeviceContext>(
> -        _dev: &kernel::drm::Device<TyrDrmDriver, Ctx>,
> +        _dev: &TyrDrmDevice<Ctx>,
>          _size: usize,
> -        _args: (),
> +        args: BoCreateArgs,
>      ) -> impl PinInit<Self, Error> {
> -        try_pin_init!(BoData {})
> +        try_pin_init!(Self { flags: args.flags })
>      }
>  }
> +
> +/// Type alias for Tyr GEM buffer objects.
> +pub(crate) type Bo = gem::shmem::Object<BoData>;
> +
> +/// Creates a dummy GEM object to serve as the root of a GPUVM.
> +#[expect(dead_code)]
> +pub(crate) fn new_dummy_object<Ctx: DeviceContext>(ddev: &TyrDrmDevice<Ctx>) -> Result<ARef<Bo>> {
> +    let bo = gem::shmem::Object::<BoData>::new(
> +        ddev,
> +        4096,
> +        shmem::ObjectConfig {
> +            map_wc: true,
> +            parent_resv_obj: None,
> +        },
> +        BoCreateArgs { flags: 0 },
> +    )?;
> +
> +    Ok(bo)
> +}

Nit: I'd probably move this new_dummy_object() addition to the commit
introducing Vm support.