[PATCH 1/2] drm/panic: use `div_ceil` to clean Clippy warning

[Miguel Ojeda]

On Sun, Mar 2, 2025 at 12:17 AM Miguel Ojeda <ojeda at kernel.org> wrote:
>
> 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 at kernel.org>

Cc: stable at vger.kernel.org # Needed in 6.12.y and 6.13.y only (Rust is
pinned in older LTSs).

Cheers,
Miguel