[PATCH v2 7/7] gpu: nova-core: firmware: gsp: use dma::Coherent for level0 table

Alexandre Courbot
2026-03-26T15:22:51Z

Replace the nova-core local `DmaObject` with a `CoherentBox` that can
fulfill the same role.

Since `CoherentBox` is more flexible than `DmaObject`, we can use the
native `u64` type for page table entries instead of messing with bytes.

The `dma` module becomes unused with that change, so remove it as well.

Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
drivers/gpu/nova-core/dma.rs | 53 -----------------------------------
drivers/gpu/nova-core/firmware/gsp.rs | 22 ++++++++-------
drivers/gpu/nova-core/nova_core.rs | 1 -
3 files changed, 12 insertions(+), 64 deletions(-)

diff --git a/drivers/gpu/nova-core/dma.rs b/drivers/gpu/nova-core/dma.rs
deleted file mode 100644
index 3c19d5ffcfe8..000000000000
--- a/drivers/gpu/nova-core/dma.rs
+++ /dev/null
@@ -1,53 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Simple DMA object wrapper.
-
-use core::ops::{
- Deref,
- DerefMut, //
-};
-
-use kernel::{
- device,
- dma::Coherent,
- page::PAGE_SIZE,
- prelude::*, //
-};
-
-pub(crate) struct DmaObject {
- dma: Coherent<[u8]>,
-}
-
-impl DmaObject {
- pub(crate) fn new(dev: &device::Device<device::Bound>, len: usize) -> Result<Self> {
- let len = core::alloc::Layout::from_size_align(len, PAGE_SIZE)
- .map_err(|_| EINVAL)?
- .pad_to_align()
- .size();
- let dma = Coherent::zeroed_slice(dev, len, GFP_KERNEL)?;
-
- Ok(Self { dma })
- }
-
- pub(crate) fn from_data(dev: &device::Device<device::Bound>, data: &[u8]) -> Result<Self> {
- let dma_obj = Self::new(dev, data.len())?;
- // SAFETY: We have just allocated the DMA memory, we are the only users and
- // we haven't made the device aware of the handle yet.
- unsafe { dma_obj.as_mut()[..data.len()].copy_from_slice(data) };
- Ok(dma_obj)
- }
-}
-
-impl Deref for DmaObject {
- type Target = Coherent<[u8]>;
-
- fn deref(&self) -> &Self::Target {
- &self.dma
- }
-}
-
-impl DerefMut for DmaObject {
- fn deref_mut(&mut self) -> &mut Self::Target {
- &mut self.dma
- }
-}
diff --git a/drivers/gpu/nova-core/firmware/gsp.rs b/drivers/gpu/nova-core/firmware/gsp.rs
index 1e0d545a74fe..86fb3f074195 100644
--- a/drivers/gpu/nova-core/firmware/gsp.rs
+++ b/drivers/gpu/nova-core/firmware/gsp.rs
@@ -4,10 +4,10 @@
device,
dma::{
Coherent,
+ CoherentBox,
DataDirection,
DmaAddress, //
},
- kvec,
prelude::*,
scatterlist::{
Owned,
@@ -16,7 +16,6 @@
};

use crate::{
- dma::DmaObject,
firmware::riscv::RiscvFirmware,
gpu::{
Architecture,
@@ -137,7 +136,7 @@ pub(crate) struct GspFirmware {
#[pin]
level1: SGTable<Owned<VVec<u8>>>,
/// Level 0 page table (single 4KB page) with one entry: DMA address of first level 1 page.
- level0: DmaObject,
+ level0: Coherent<[u64]>,
/// Size in bytes of the firmware contained in [`Self::fw`].
pub(crate) size: usize,
/// Device-mapped GSP signatures matching the GPU's [`Chipset`].
@@ -198,17 +197,20 @@ pub(crate) fn new<'a>(
// Allocate the level 0 page table as a device-visible DMA object, and map the
// level 1 page table onto it.

- // Level 0 page table data.
- let mut level0_data = kvec![0u8; GSP_PAGE_SIZE]?;
-
// Fill level 1 page entry.
let level1_entry = level1.iter().next().ok_or(EINVAL)?;
let level1_entry_addr = level1_entry.dma_address();
- let dst = &mut level0_data[..size_of_val(&level1_entry_addr)];
- dst.copy_from_slice(&level1_entry_addr.to_le_bytes());

- // Turn the level0 page table into a [`DmaObject`].
- DmaObject::from_data(dev, &level0_data)?
+ // Create level 0 page table data and fill its first entry with the level 1
+ // table.
+ let mut level0 = CoherentBox::<[u64]>::zeroed_slice(
+ dev,
+ GSP_PAGE_SIZE / size_of::<u64>(),
+ GFP_KERNEL
+ )?;
+ level0[0] = level1_entry_addr.to_le();
+
+ level0.into()
},
size,
signatures: {
diff --git a/drivers/gpu/nova-core/nova_core.rs b/drivers/gpu/nova-core/nova_core.rs
index 98675c69d2b7..04a1fa6b25f8 100644
--- a/drivers/gpu/nova-core/nova_core.rs
+++ b/drivers/gpu/nova-core/nova_core.rs
@@ -13,7 +13,6 @@
#[macro_use]
mod bitfield;

-mod dma;
mod driver;
mod falcon;
mod fb;

--
2.53.0