Hi Lyude,
> On 5 Mar 2025, at 19:59, Lyude Paul <ly...@redhat.com> wrote:
>
> This adds some very basic rust bindings for fourcc. We only have a single
> format code added for the moment, but this is enough to get a driver
> registered.
>
> Signed-off-by: Lyude Paul <ly...@redhat.com>
>
> ---
> V3:
> * Drop FormatList and ModifierList
> These aren't actually needed as pointed out by Louis Chauvet
> * Add a constant for FORMAT_MOD_INVALID
> I realized that we actually need this because the format list isn't
> terminated with a 0 like I thought, and we can't pick this up
> automatically through bindgen
> * Split out the FormatInfo WIP
> We'll want this someday, but not yet.
>
> Signed-off-by: Lyude Paul <ly...@redhat.com>
> ---
> rust/kernel/drm/fourcc.rs | 21 +++++++++++++++++++++
> rust/kernel/drm/mod.rs | 1 +
> 2 files changed, 22 insertions(+)
> create mode 100644 rust/kernel/drm/fourcc.rs
>
> diff --git a/rust/kernel/drm/fourcc.rs b/rust/kernel/drm/fourcc.rs
> new file mode 100644
> index 0000000000000..62203478b5955
> --- /dev/null
> +++ b/rust/kernel/drm/fourcc.rs
> @@ -0,0 +1,21 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +//! DRM fourcc bindings.
> +//!
> +//! C header:
> [`include/uapi/drm/drm_fourcc.h`](srctree/include/uapi/drm/drm_fourcc.h)
> +
> +/// Return a fourcc format code.
> +const fn fourcc_code(a: u8, b: u8, c: u8, d: u8) -> u32 {
> + (a as u32) | (b as u32) << 8 | (c as u32) << 16 | (d as u32) << 24
> +}
> +
> +// TODO: We manually import this because we don't have a reasonable way of
> getting constants from
> +// function-like macros in bindgen yet.
> +#[allow(dead_code)]
> +pub(crate) const FORMAT_MOD_INVALID: u64 = 0xffffffffffffff;
Isn’t this just u64::MAX?
> +
> +// TODO: We need to automate importing all of these. For the time being,
> just add the single one
> +// that we need
> +
> +/// 32 bpp RGB
> +pub const XRGB888: u32 = fourcc_code(b'X', b'R', b'2', b'4');
> diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs
> index c44760a1332fa..2c12dbd181997 100644
> --- a/rust/kernel/drm/mod.rs
> +++ b/rust/kernel/drm/mod.rs
> @@ -5,5 +5,6 @@
> pub mod device;
> pub mod drv;
> pub mod file;
> +pub mod fourcc;
> pub mod gem;
> pub mod ioctl;
> --
> 2.48.1
>
>
