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

[Deborah Brouwer <deborah.brouwer@collabora.com>]

On Thu, Feb 12, 2026 at 09:17:34AM +0100, Boris Brezillon wrote:
> 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.

Ok that works too.

>