Re: [PATCH 2/7] gpu: nova-core: firmware: riscv: use dma::Coherent

["Gary Guo" <gary@garyguo.net>]

On Sat Mar 21, 2026 at 1:36 PM GMT, Alexandre Courbot wrote:
> Replace the nova-core local `DmaObject` with a `Coherent` that can
> fulfill the same role.
>
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
>  drivers/gpu/nova-core/firmware/riscv.rs | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/nova-core/firmware/riscv.rs b/drivers/gpu/nova-core/firmware/riscv.rs
> index 14aad2f0ee8a..2afa7f36404e 100644
> --- a/drivers/gpu/nova-core/firmware/riscv.rs
> +++ b/drivers/gpu/nova-core/firmware/riscv.rs
> @@ -5,13 +5,13 @@
>  
>  use kernel::{
>      device,
> +    dma::Coherent,
>      firmware::Firmware,
>      prelude::*,
>      transmute::FromBytes, //
>  };
>  
>  use crate::{
> -    dma::DmaObject,
>      firmware::BinFirmware,
>      num::FromSafeCast, //
>  };
> @@ -66,7 +66,7 @@ pub(crate) struct RiscvFirmware {
>      /// Application version.
>      pub(crate) app_version: u32,
>      /// Device-mapped firmware image.
> -    pub(crate) ucode: DmaObject,
> +    pub(crate) ucode: Coherent<[u8]>,
>  }
>  
>  impl RiscvFirmware {
> @@ -81,7 +81,7 @@ pub(crate) fn new(dev: &device::Device<device::Bound>, fw: &Firmware) -> Result<
>              let len = usize::from_safe_cast(bin_fw.hdr.data_size);
>              let end = start.checked_add(len).ok_or(EINVAL)?;
>  
> -            DmaObject::from_data(dev, fw.data().get(start..end).ok_or(EINVAL)?)?
> +            Coherent::from_slice(dev, fw.data().get(start..end).ok_or(EINVAL)?, GFP_KERNEL)?

`DmaObject` rounds the data up to be page-sized, while this new API doesn't.

It has impact on alignment, as the allocator aligns things to the largest
power-of-two exponent of the allocated size.

Best,
Gary

>          };
>  
>          Ok(Self {