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Message-ID: <1492791271.25675.57.camel@redhat.com>
Subject: Re: [PATCH] drm: fourcc byteorder: brings header file comments in
 line with reality.
From: Gerd Hoffmann <kraxel@redhat.com>
To: Christian =?ISO-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>
Cc: Ville =?ISO-8859-1?Q?Syrj=E4l=E4?= 
        <ville.syrjala@linux.intel.com>,
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        open list <linux-kernel@vger.kernel.org>,
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        Alex Deucher <alexdeucher@gmail.com>,
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        Ilia Mirkin <imirkin@alum.mit.edu>
Date: Fri, 21 Apr 2017 18:14:31 +0200
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  Hi,

> > My personal opinion is that formats in drm_fourcc.h should be 
> > independent of the CPU byte order and the function 
> > drm_mode_legacy_fb_format() and drivers depending on that incorrect 
> > assumption be fixed instead.
> 
> The problem is this isn't a kernel-internal thing any more.  With the
> addition of the ADDFB2 ioctl the fourcc codes became part of the
> kernel/userspace abi ...

Ok, added some printk's to the ADDFB and ADDFB2 code paths and tested a
bit.  Apparently pretty much all userspace still uses the ADDFB ioctl.
xorg (modesetting driver) does.  gnome-shell in wayland mode does.
Seems the big transition to ADDFB2 didn't happen yet.

I guess that makes changing drm_mode_legacy_fb_format + drivers a
reasonable option ...

cheers,
  Gerd