linux-kernel - Re: [PATCH 1/3] drm: fourcc byteorder: drop DRM_FORMAT_BIG

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Date:   Tue, 02 May 2017 16:14:24 +0200
From:   Gerd Hoffmann <kraxel@...hat.com>
To:     Emil Velikov <emil.l.velikov@...il.com>
Cc:     ML dri-devel <dri-devel@...ts.freedesktop.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>,
        Michel Dänzer <michel@...nzer.net>,
        open list <linux-kernel@...r.kernel.org>,
        amd-gfx mailing list <amd-gfx@...ts.freedesktop.org>,
        Pekka Paalanen <ppaalanen@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Alex Deucher <alexdeucher@...il.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Ilia Mirkin <imirkin@...m.mit.edu>
Subject: Re: [PATCH 1/3] drm: fourcc byteorder: drop DRM_FORMAT_BIG_ENDIAN

> > diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> > index 995c8f9c69..305bc34be0 100644
> > --- a/include/uapi/drm/drm_fourcc.h
> > +++ b/include/uapi/drm/drm_fourcc.h
> > @@ -33,8 +33,6 @@ extern "C" {
> >  #define fourcc_code(a, b, c, d) ((__u32)(a) | ((__u32)(b) << 8) | \
> >                                  ((__u32)(c) << 16) | ((__u32)(d) << 24))
> >
> > -#define DRM_FORMAT_BIG_ENDIAN (1<<31) /* format is big endian instead of little endian */
> > -
> 
> Weston references DRM_FORMAT_BIG_ENDIAN thus this patch will lead to
> build breakage.

> Personally I would leave the symbol, since it's UAPI and document that
> should not be used.

Fair enough.  I can surely add a deprecated comment instead of just
dropping it.

I'm wondering how it is used though, given that none of the drivers in
the kernel actually  support this flag ...

cheers,
  Gerd