linux-kernel - [PATCH 1/2] drm/panic: use `div

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Message-ID: <20250301231602.917580-1-ojeda@kernel.org>
Date: Sun,  2 Mar 2025 00:16:01 +0100
From: Miguel Ojeda <ojeda@...nel.org>
To: Jocelyn Falempe <jfalempe@...hat.com>,
	Thomas Böhler <witcher@...edspace.de>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>
Cc: dri-devel@...ts.freedesktop.org,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev
Subject: [PATCH 1/2] drm/panic: use `div_ceil` to clean Clippy warning

Starting with the upcoming Rust 1.86.0 (to be released 2025-04-03),
Clippy warns:

    error: manually reimplementing `div_ceil`
       --> drivers/gpu/drm/drm_panic_qr.rs:548:26
        |
    548 |         let pad_offset = (offset + 7) / 8;
        |                          ^^^^^^^^^^^^^^^^ help: consider using `.div_ceil()`: `offset.div_ceil(8)`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_div_ceil

And similarly for `stride`. Thus apply the suggestion to both.

The behavior (and thus codegen) is not exactly equivalent [1][2], since
`div_ceil()` returns the right value for the values that currently
would overflow.

Link: https://github.com/rust-lang/rust-clippy/issues/14333 [1]
Link: https://godbolt.org/z/dPq6nGnv3 [2]
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
 drivers/gpu/drm/drm_panic_qr.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs
index bcf248f69252..8bb5e52d75cc 100644
--- a/drivers/gpu/drm/drm_panic_qr.rs
+++ b/drivers/gpu/drm/drm_panic_qr.rs
@@ -545,7 +545,7 @@ fn add_segments(&mut self, segments: &[&Segment<'_>]) {
         }
         self.push(&mut offset, (MODE_STOP, 4));
 
-        let pad_offset = (offset + 7) / 8;
+        let pad_offset = offset.div_ceil(8);
         for i in pad_offset..self.version.max_data() {
             self.data[i] = PADDING[(i & 1) ^ (pad_offset & 1)];
         }
@@ -659,7 +659,7 @@ struct QrImage<'a> {
 impl QrImage<'_> {
     fn new<'a, 'b>(em: &'b EncodedMsg<'b>, qrdata: &'a mut [u8]) -> QrImage<'a> {
         let width = em.version.width();
-        let stride = (width + 7) / 8;
+        let stride = width.div_ceil(8);
         let data = qrdata;
 
         let mut qr_image = QrImage {

base-commit: d082ecbc71e9e0bf49883ee4afd435a77a5101b6
-- 
2.48.1