On Mon, 7 Mar 2022 21:53:42 +0100
Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> DRM formats are defined to be little-endian, unless the
> DRM_FORMAT_BIG_ENDIAN flag is set. Hence writes of multi-byte pixel
> values need to take endianness into account.
>
> Introduce a cpu_to_le32() helper to convert 32-bit values from
> CPU-endian to little-endian, and use them in the various pattern fill
> functions for 32-bit formats.
Hi Geert,
FWIW, this explanation matches my understanding, so it sounds correct
to me. That's all I can say. I guess that means
Acked-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx>
?
Thanks,
pq
>
> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> ---
> Works now with Linux' drm_fb_xrgb8888_to_rgb332_line(), which uses
> le32_to_cpu() to read pixel values from memory.
>
> ---
> tests/util/pattern.c | 30 +++++++++++++++++++++---------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/tests/util/pattern.c b/tests/util/pattern.c
> index 42d75d700700dc3d..48677ea6d25b2676 100644
> --- a/tests/util/pattern.c
> +++ b/tests/util/pattern.c
> @@ -61,6 +61,18 @@ struct color_yuv {
> .u = MAKE_YUV_601_U(r, g, b), \
> .v = MAKE_YUV_601_V(r, g, b) }
>
> +#if defined(__BIG_ENDIAN__) || defined(__sparc__) || defined(__mc68000__) || defined(__MIPSEB__)
> +static inline uint32_t cpu_to_le32(uint32_t x)
> +{
> + return ((x & 0x000000ffU) << 24) |
> + ((x & 0x0000ff00U) << 8) |
> + ((x & 0x00ff0000U) >> 8) |
> + ((x & 0xff000000U) >> 24);
> +}
> +#else
> +#define cpu_to_le32(x) (x)
> +#endif
Attachment:
pgpXDo6f7yy12.pgp
Description: OpenPGP digital signature
