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    SubjectRe: [PATCH] drm: fourcc byteorder: brings header file comments in line with reality.
    On Fri, Apr 21, 2017 at 11:50:18AM +0200, Gerd Hoffmann wrote:
    > On Fr, 2017-04-21 at 12:25 +0300, Ville Syrjälä wrote:
    > > 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.
    >
    > native == whatever the cpu is using.
    >
    > I personally find "native" more intuitive, but at the end of the day I
    > don't mind much. If people prefer "host" over "native" I'll change it.
    >
    > > And what about the mxied endian case? Are you just going to pretend it
    > > doesn't exist or what?
    >
    > What exactly do you mean with "mixed endian"? The powerpc case, where
    > kernel + userspace can run in either big or little endian mode? Or
    > something else?

    Big endian CPU and little endian GPU. I think that should be the most
    common case these days.

    --
    Ville Syrjälä
    Intel OTC

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