[PATCH] drm: fourcc byteorder: brings header file comments in line with reality.

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On Fri, Apr 21, 2017 at 09:58:24AM +0200, Gerd Hoffmann wrote:
> While working on graphics support for virtual machines on ppc64 (which
> exists in both little and big endian variants) I've figured the comments
> for various drm fourcc formats in the header file don't match reality.
> 
> Comments says the RGB formats are little endian, but in practice they
> are native endian.  Look at the drm_mode_legacy_fb_format() helper.  It
> maps -- for example -- bpp/depth 32/24 to DRM_FORMAT_XRGB8888, no matter
> whenever the machine is little endian or big endian.  The users of this
> function (fbdev emulation, DRM_IOCTL_MODE_ADDFB) expect the framebuffer
> is native endian, not little endian.  Most userspace also operates on
> native endian only.

I'm not a fan of "native". Native to what? "CPU" or "host" is what I'd
call it.

And what about the mxied endian case? Are you just going to pretend it
doesn't exist or what?

> 
> So, go update the comments for all 16+24+32 bpp RGB formats.
> 
> Leaving the yuv formats as-is.  I have no idea if and how those are used
> on bigendian machines.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Pekka Paalanen <ppaalanen at gmail.com>
> Cc: Ilia Mirkin <imirkin at alum.mit.edu>
> Cc: Michel Dänzer <michel at daenzer.net>
> Cc: Alex Deucher <alexdeucher at gmail.com>
> Cc: amd-gfx at lists.freedesktop.org
> Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> ---
>  include/uapi/drm/drm_fourcc.h | 82 +++++++++++++++++++++----------------------
>  1 file changed, 41 insertions(+), 41 deletions(-)
> 
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index 995c8f9..1579765 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -42,68 +42,68 @@ extern "C" {
>  #define DRM_FORMAT_R8		fourcc_code('R', '8', ' ', ' ') /* [7:0] R */
>  
>  /* 16 bpp Red */
> -#define DRM_FORMAT_R16		fourcc_code('R', '1', '6', ' ') /* [15:0] R little endian */
> +#define DRM_FORMAT_R16		fourcc_code('R', '1', '6', ' ') /* [15:0] R native endian */
>  
>  /* 16 bpp RG */
> -#define DRM_FORMAT_RG88		fourcc_code('R', 'G', '8', '8') /* [15:0] R:G 8:8 little endian */
> -#define DRM_FORMAT_GR88		fourcc_code('G', 'R', '8', '8') /* [15:0] G:R 8:8 little endian */
> +#define DRM_FORMAT_RG88		fourcc_code('R', 'G', '8', '8') /* [15:0] R:G 8:8 native endian */
> +#define DRM_FORMAT_GR88		fourcc_code('G', 'R', '8', '8') /* [15:0] G:R 8:8 native endian */
>  
>  /* 32 bpp RG */
> -#define DRM_FORMAT_RG1616	fourcc_code('R', 'G', '3', '2') /* [31:0] R:G 16:16 little endian */
> -#define DRM_FORMAT_GR1616	fourcc_code('G', 'R', '3', '2') /* [31:0] G:R 16:16 little endian */
> +#define DRM_FORMAT_RG1616	fourcc_code('R', 'G', '3', '2') /* [31:0] R:G 16:16 native endian */
> +#define DRM_FORMAT_GR1616	fourcc_code('G', 'R', '3', '2') /* [31:0] G:R 16:16 native endian */
>  
>  /* 8 bpp RGB */
>  #define DRM_FORMAT_RGB332	fourcc_code('R', 'G', 'B', '8') /* [7:0] R:G:B 3:3:2 */
>  #define DRM_FORMAT_BGR233	fourcc_code('B', 'G', 'R', '8') /* [7:0] B:G:R 2:3:3 */
>  
>  /* 16 bpp RGB */
> -#define DRM_FORMAT_XRGB4444	fourcc_code('X', 'R', '1', '2') /* [15:0] x:R:G:B 4:4:4:4 little endian */
> -#define DRM_FORMAT_XBGR4444	fourcc_code('X', 'B', '1', '2') /* [15:0] x:B:G:R 4:4:4:4 little endian */
> -#define DRM_FORMAT_RGBX4444	fourcc_code('R', 'X', '1', '2') /* [15:0] R:G:B:x 4:4:4:4 little endian */
> -#define DRM_FORMAT_BGRX4444	fourcc_code('B', 'X', '1', '2') /* [15:0] B:G:R:x 4:4:4:4 little endian */
> +#define DRM_FORMAT_XRGB4444	fourcc_code('X', 'R', '1', '2') /* [15:0] x:R:G:B 4:4:4:4 native endian */
> +#define DRM_FORMAT_XBGR4444	fourcc_code('X', 'B', '1', '2') /* [15:0] x:B:G:R 4:4:4:4 native endian */
> +#define DRM_FORMAT_RGBX4444	fourcc_code('R', 'X', '1', '2') /* [15:0] R:G:B:x 4:4:4:4 native endian */
> +#define DRM_FORMAT_BGRX4444	fourcc_code('B', 'X', '1', '2') /* [15:0] B:G:R:x 4:4:4:4 native endian */
>  
> -#define DRM_FORMAT_ARGB4444	fourcc_code('A', 'R', '1', '2') /* [15:0] A:R:G:B 4:4:4:4 little endian */
> -#define DRM_FORMAT_ABGR4444	fourcc_code('A', 'B', '1', '2') /* [15:0] A:B:G:R 4:4:4:4 little endian */
> -#define DRM_FORMAT_RGBA4444	fourcc_code('R', 'A', '1', '2') /* [15:0] R:G:B:A 4:4:4:4 little endian */
> -#define DRM_FORMAT_BGRA4444	fourcc_code('B', 'A', '1', '2') /* [15:0] B:G:R:A 4:4:4:4 little endian */
> +#define DRM_FORMAT_ARGB4444	fourcc_code('A', 'R', '1', '2') /* [15:0] A:R:G:B 4:4:4:4 native endian */
> +#define DRM_FORMAT_ABGR4444	fourcc_code('A', 'B', '1', '2') /* [15:0] A:B:G:R 4:4:4:4 native endian */
> +#define DRM_FORMAT_RGBA4444	fourcc_code('R', 'A', '1', '2') /* [15:0] R:G:B:A 4:4:4:4 native endian */
> +#define DRM_FORMAT_BGRA4444	fourcc_code('B', 'A', '1', '2') /* [15:0] B:G:R:A 4:4:4:4 native endian */
>  
> -#define DRM_FORMAT_XRGB1555	fourcc_code('X', 'R', '1', '5') /* [15:0] x:R:G:B 1:5:5:5 little endian */
> -#define DRM_FORMAT_XBGR1555	fourcc_code('X', 'B', '1', '5') /* [15:0] x:B:G:R 1:5:5:5 little endian */
> -#define DRM_FORMAT_RGBX5551	fourcc_code('R', 'X', '1', '5') /* [15:0] R:G:B:x 5:5:5:1 little endian */
> -#define DRM_FORMAT_BGRX5551	fourcc_code('B', 'X', '1', '5') /* [15:0] B:G:R:x 5:5:5:1 little endian */
> +#define DRM_FORMAT_XRGB1555	fourcc_code('X', 'R', '1', '5') /* [15:0] x:R:G:B 1:5:5:5 native endian */
> +#define DRM_FORMAT_XBGR1555	fourcc_code('X', 'B', '1', '5') /* [15:0] x:B:G:R 1:5:5:5 native endian */
> +#define DRM_FORMAT_RGBX5551	fourcc_code('R', 'X', '1', '5') /* [15:0] R:G:B:x 5:5:5:1 native endian */
> +#define DRM_FORMAT_BGRX5551	fourcc_code('B', 'X', '1', '5') /* [15:0] B:G:R:x 5:5:5:1 native endian */
>  
> -#define DRM_FORMAT_ARGB1555	fourcc_code('A', 'R', '1', '5') /* [15:0] A:R:G:B 1:5:5:5 little endian */
> -#define DRM_FORMAT_ABGR1555	fourcc_code('A', 'B', '1', '5') /* [15:0] A:B:G:R 1:5:5:5 little endian */
> -#define DRM_FORMAT_RGBA5551	fourcc_code('R', 'A', '1', '5') /* [15:0] R:G:B:A 5:5:5:1 little endian */
> -#define DRM_FORMAT_BGRA5551	fourcc_code('B', 'A', '1', '5') /* [15:0] B:G:R:A 5:5:5:1 little endian */
> +#define DRM_FORMAT_ARGB1555	fourcc_code('A', 'R', '1', '5') /* [15:0] A:R:G:B 1:5:5:5 native endian */
> +#define DRM_FORMAT_ABGR1555	fourcc_code('A', 'B', '1', '5') /* [15:0] A:B:G:R 1:5:5:5 native endian */
> +#define DRM_FORMAT_RGBA5551	fourcc_code('R', 'A', '1', '5') /* [15:0] R:G:B:A 5:5:5:1 native endian */
> +#define DRM_FORMAT_BGRA5551	fourcc_code('B', 'A', '1', '5') /* [15:0] B:G:R:A 5:5:5:1 native endian */
>  
> -#define DRM_FORMAT_RGB565	fourcc_code('R', 'G', '1', '6') /* [15:0] R:G:B 5:6:5 little endian */
> -#define DRM_FORMAT_BGR565	fourcc_code('B', 'G', '1', '6') /* [15:0] B:G:R 5:6:5 little endian */
> +#define DRM_FORMAT_RGB565	fourcc_code('R', 'G', '1', '6') /* [15:0] R:G:B 5:6:5 native endian */
> +#define DRM_FORMAT_BGR565	fourcc_code('B', 'G', '1', '6') /* [15:0] B:G:R 5:6:5 native endian */
>  
>  /* 24 bpp RGB */
> -#define DRM_FORMAT_RGB888	fourcc_code('R', 'G', '2', '4') /* [23:0] R:G:B little endian */
> -#define DRM_FORMAT_BGR888	fourcc_code('B', 'G', '2', '4') /* [23:0] B:G:R little endian */
> +#define DRM_FORMAT_RGB888	fourcc_code('R', 'G', '2', '4') /* [23:0] R:G:B native endian */
> +#define DRM_FORMAT_BGR888	fourcc_code('B', 'G', '2', '4') /* [23:0] B:G:R native endian */
>  
>  /* 32 bpp RGB */
> -#define DRM_FORMAT_XRGB8888	fourcc_code('X', 'R', '2', '4') /* [31:0] x:R:G:B 8:8:8:8 little endian */
> -#define DRM_FORMAT_XBGR8888	fourcc_code('X', 'B', '2', '4') /* [31:0] x:B:G:R 8:8:8:8 little endian */
> -#define DRM_FORMAT_RGBX8888	fourcc_code('R', 'X', '2', '4') /* [31:0] R:G:B:x 8:8:8:8 little endian */
> -#define DRM_FORMAT_BGRX8888	fourcc_code('B', 'X', '2', '4') /* [31:0] B:G:R:x 8:8:8:8 little endian */
> +#define DRM_FORMAT_XRGB8888	fourcc_code('X', 'R', '2', '4') /* [31:0] x:R:G:B 8:8:8:8 native endian */
> +#define DRM_FORMAT_XBGR8888	fourcc_code('X', 'B', '2', '4') /* [31:0] x:B:G:R 8:8:8:8 native endian */
> +#define DRM_FORMAT_RGBX8888	fourcc_code('R', 'X', '2', '4') /* [31:0] R:G:B:x 8:8:8:8 native endian */
> +#define DRM_FORMAT_BGRX8888	fourcc_code('B', 'X', '2', '4') /* [31:0] B:G:R:x 8:8:8:8 native endian */
>  
> -#define DRM_FORMAT_ARGB8888	fourcc_code('A', 'R', '2', '4') /* [31:0] A:R:G:B 8:8:8:8 little endian */
> -#define DRM_FORMAT_ABGR8888	fourcc_code('A', 'B', '2', '4') /* [31:0] A:B:G:R 8:8:8:8 little endian */
> -#define DRM_FORMAT_RGBA8888	fourcc_code('R', 'A', '2', '4') /* [31:0] R:G:B:A 8:8:8:8 little endian */
> -#define DRM_FORMAT_BGRA8888	fourcc_code('B', 'A', '2', '4') /* [31:0] B:G:R:A 8:8:8:8 little endian */
> +#define DRM_FORMAT_ARGB8888	fourcc_code('A', 'R', '2', '4') /* [31:0] A:R:G:B 8:8:8:8 native endian */
> +#define DRM_FORMAT_ABGR8888	fourcc_code('A', 'B', '2', '4') /* [31:0] A:B:G:R 8:8:8:8 native endian */
> +#define DRM_FORMAT_RGBA8888	fourcc_code('R', 'A', '2', '4') /* [31:0] R:G:B:A 8:8:8:8 native endian */
> +#define DRM_FORMAT_BGRA8888	fourcc_code('B', 'A', '2', '4') /* [31:0] B:G:R:A 8:8:8:8 native endian */
>  
> -#define DRM_FORMAT_XRGB2101010	fourcc_code('X', 'R', '3', '0') /* [31:0] x:R:G:B 2:10:10:10 little endian */
> -#define DRM_FORMAT_XBGR2101010	fourcc_code('X', 'B', '3', '0') /* [31:0] x:B:G:R 2:10:10:10 little endian */
> -#define DRM_FORMAT_RGBX1010102	fourcc_code('R', 'X', '3', '0') /* [31:0] R:G:B:x 10:10:10:2 little endian */
> -#define DRM_FORMAT_BGRX1010102	fourcc_code('B', 'X', '3', '0') /* [31:0] B:G:R:x 10:10:10:2 little endian */
> +#define DRM_FORMAT_XRGB2101010	fourcc_code('X', 'R', '3', '0') /* [31:0] x:R:G:B 2:10:10:10 native endian */
> +#define DRM_FORMAT_XBGR2101010	fourcc_code('X', 'B', '3', '0') /* [31:0] x:B:G:R 2:10:10:10 native endian */
> +#define DRM_FORMAT_RGBX1010102	fourcc_code('R', 'X', '3', '0') /* [31:0] R:G:B:x 10:10:10:2 native endian */
> +#define DRM_FORMAT_BGRX1010102	fourcc_code('B', 'X', '3', '0') /* [31:0] B:G:R:x 10:10:10:2 native endian */
>  
> -#define DRM_FORMAT_ARGB2101010	fourcc_code('A', 'R', '3', '0') /* [31:0] A:R:G:B 2:10:10:10 little endian */
> -#define DRM_FORMAT_ABGR2101010	fourcc_code('A', 'B', '3', '0') /* [31:0] A:B:G:R 2:10:10:10 little endian */
> -#define DRM_FORMAT_RGBA1010102	fourcc_code('R', 'A', '3', '0') /* [31:0] R:G:B:A 10:10:10:2 little endian */
> -#define DRM_FORMAT_BGRA1010102	fourcc_code('B', 'A', '3', '0') /* [31:0] B:G:R:A 10:10:10:2 little endian */
> +#define DRM_FORMAT_ARGB2101010	fourcc_code('A', 'R', '3', '0') /* [31:0] A:R:G:B 2:10:10:10 native endian */
> +#define DRM_FORMAT_ABGR2101010	fourcc_code('A', 'B', '3', '0') /* [31:0] A:B:G:R 2:10:10:10 native endian */
> +#define DRM_FORMAT_RGBA1010102	fourcc_code('R', 'A', '3', '0') /* [31:0] R:G:B:A 10:10:10:2 native endian */
> +#define DRM_FORMAT_BGRA1010102	fourcc_code('B', 'A', '3', '0') /* [31:0] B:G:R:A 10:10:10:2 native endian */
>  
>  /* packed YCbCr */
>  #define DRM_FORMAT_YUYV		fourcc_code('Y', 'U', 'Y', 'V') /* [31:0] Cr0:Y1:Cb0:Y0 8:8:8:8 little endian */
> -- 
> 2.9.3

-- 
Ville Syrjälä
Intel OTC


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