linux-kernel - [PATCH v4 2/2] gpu: nova-core: use Alignment for alignment-related operations

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Message-Id: <20250821-num-v4-2-1f3a425d7244@nvidia.com>
Date: Thu, 21 Aug 2025 21:42:18 +0900
From: Alexandre Courbot <acourbot@...dia.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <lossin@...nel.org>, Andreas Hindborg <a.hindborg@...nel.org>, 
 Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, 
 Danilo Krummrich <dakr@...nel.org>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org, 
 nouveau@...ts.freedesktop.org, Alexandre Courbot <acourbot@...dia.com>
Subject: [PATCH v4 2/2] gpu: nova-core: use Alignment for alignment-related
 operations

Make use of the newly-available `Alignment` type and remove the
corresponding TODO item.

Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
---
 Documentation/gpu/nova/core/todo.rst | 1 -
 drivers/gpu/nova-core/fb.rs          | 6 +++---
 drivers/gpu/nova-core/vbios.rs       | 4 ++--
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/Documentation/gpu/nova/core/todo.rst b/Documentation/gpu/nova/core/todo.rst
index 48b20656dcb16056db7784fa186f161126aae9aa..89431fec9041b1f35cc55799c91f48dc6bc918eb 100644
--- a/Documentation/gpu/nova/core/todo.rst
+++ b/Documentation/gpu/nova/core/todo.rst
@@ -145,7 +145,6 @@ Numerical operations [NUMM]
 Nova uses integer operations that are not part of the standard library (or not
 implemented in an optimized way for the kernel). These include:
 
-- Aligning up and down to a power of two,
 - The "Find Last Set Bit" (`fls` function of the C part of the kernel)
   operation.
 
diff --git a/drivers/gpu/nova-core/fb.rs b/drivers/gpu/nova-core/fb.rs
index 4a702525fff4f394b75fcf54145ba78e34a1a539..344cb5d2d919c456212d60d7210667de8041f812 100644
--- a/drivers/gpu/nova-core/fb.rs
+++ b/drivers/gpu/nova-core/fb.rs
@@ -3,6 +3,7 @@
 use core::ops::Range;
 
 use kernel::prelude::*;
+use kernel::ptr::{Alignable, Alignment};
 use kernel::sizes::*;
 use kernel::types::ARef;
 use kernel::{dev_warn, device};
@@ -130,10 +131,9 @@ pub(crate) fn new(chipset: Chipset, bar: &Bar0) -> Result<Self> {
         };
 
         let frts = {
-            const FRTS_DOWN_ALIGN: u64 = SZ_128K as u64;
+            const FRTS_DOWN_ALIGN: Alignment = Alignment::new(SZ_128K);
             const FRTS_SIZE: u64 = SZ_1M as u64;
-            // TODO[NUMM]: replace with `align_down` once it lands.
-            let frts_base = (vga_workspace.start & !(FRTS_DOWN_ALIGN - 1)) - FRTS_SIZE;
+            let frts_base = vga_workspace.start.align_down(FRTS_DOWN_ALIGN) - FRTS_SIZE;
 
             frts_base..frts_base + FRTS_SIZE
         };
diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
index 50fbea69fc0038255a0a2b8f7bad57cd55eb65a2..9b81c39b11cea91a93359a239078576165a07200 100644
--- a/drivers/gpu/nova-core/vbios.rs
+++ b/drivers/gpu/nova-core/vbios.rs
@@ -10,6 +10,7 @@
 use kernel::error::Result;
 use kernel::pci;
 use kernel::prelude::*;
+use kernel::ptr::{Alignable, Alignment};
 
 /// The offset of the VBIOS ROM in the BAR0 space.
 const ROM_OFFSET: usize = 0x300000;
@@ -177,8 +178,7 @@ fn next(&mut self) -> Option<Self::Item> {
 
         // Advance to next image (aligned to 512 bytes).
         self.current_offset += image_size;
-        // TODO[NUMM]: replace with `align_up` once it lands.
-        self.current_offset = self.current_offset.next_multiple_of(512);
+        self.current_offset = self.current_offset.align_up(Alignment::new(512))?;
 
         Some(Ok(full_image))
     }

-- 
2.50.1