Re: [PATCH 3/6] drm: fourcc byteorder: add bigendian support to drm_mode_legacy_fb_format

[Ville Syrjälä]

On Wed, Apr 26, 2017 at 11:00:09AM +0900, Michel Dänzer wrote:
> On 25/04/17 06:52 PM, Ville Syrjälä wrote:
> > On Tue, Apr 25, 2017 at 12:18:52PM +0900, Michel Dänzer wrote:
> >> On 24/04/17 03:25 PM, Gerd Hoffmann wrote:
> >>> +#ifdef __BIG_ENDIAN
> >>> +	switch (bpp) {
> >>> +	case 8:
> >>> +		fmt = DRM_FORMAT_C8;
> >>> +		break;
> >>> +	case 24:
> >>> +		fmt = DRM_FORMAT_BGR888;
> >>> +		break;
> >>
> >> BTW, endianness as a concept cannot apply to 8 or 24 bpp formats.
> > 
> > To 8bpp no, but it can easily apply to 24bpp.
> 
> Any byte swapping rips apart the bytes of a 24bpp pixel, so those
> formats only make sense as straight array formats.

In my book little endian just means "lsb is stored in the lowest
memory address". The fact that your CPU/GPU can't do 3 byte swaps
is not relevant for that definition IMO.

-- 
Ville Syrjälä
Intel OTC