From mboxrd@z Thu Jan  1 00:00:00 1970
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Mon, 29 Aug 2011 14:17:12 +0000
Subject: Re: [PATCH/RFC v2 1/3] fbdev: Add FOURCC-based format configuration API
Message-Id: <201108291617.13236.laurent.pinchart@ideasonboard.com>
List-Id: <linux-fbdev.vger.kernel.org>
References: <1313746626-23845-1-git-send-email-laurent.pinchart@ideasonboard.com> <201108291534.35951.laurent.pinchart@ideasonboard.com> <CAMuHMdV=ZWMSJ_-r9fRMs0RCHyDZL=1a0_ZPZCgLBYJf=Ws4=Q@mail.gmail.com>
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To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-fbdev@vger.kernel.org, linux-media@vger.kernel.org, magnus.damm@gmail.com

Hi Geert,

On Monday 29 August 2011 16:14:38 Geert Uytterhoeven wrote:
> On Mon, Aug 29, 2011 at 15:34, Laurent Pinchart wrote:
> > On Monday 29 August 2011 15:09:04 Geert Uytterhoeven wrote:
> >> On Mon, Aug 29, 2011 at 14:55, Laurent Pinchart wrote:
> >> >> When will the driver report FB_{TYPE,VISUAL}_FOURCC?
> >> >>   - When using a mode that cannot be represented in the legacy way,
> >> >=20
> >> > Definitely.
> >> >=20
> >> >>   - But what with modes that can be represented? Legacy software
> >> >> cannot handle FB_{TYPE,VISUAL}_FOURCC.
> >> >=20
> >> > My idea was to use FB_{TYPE,VISUAL}_FOURCC only when the mode is
> >> > configured using the FOURCC API. If FBIOPUT_VSCREENINFO is called wi=
th
> >> > a non-FOURCC format, the driver will report non-FOURCC types and
> >> > visuals.
> >>=20
> >> Hmm, two use cases:
> >>   - The video mode is configured using a FOURCC-aware tool ("fbset on
> >> steroids").
> >=20
> > Such as http://git.ideasonboard.org/?p=FBdev-test.git;a=3Dsummary :-)
>=20
> Yep.
>=20
> >>     Later the user runs a legacy application.
> >>       =3D> Do not retain FOURCC across opening of /dev/fb*.
> >=20
> > I know about that problem, but it's not that easy to work around. We ha=
ve
> > no per-open fixed and variable screen info, and FB devices can be opened
> > by multiple applications at the same time.
> >=20
> >>   - Is there an easy way to force FOURCC reporting, so new apps don't
> >> have to support parsing the legacy formats? This is useful for new apps
> >> that want to support (a subset of) FOURCC modes only.
> >=20
> > Not at the moment.
>=20
> So perhaps we do need new ioctls instead...
> That would also ease an in-kernel translation layer.

Do you mean new ioctls to replace the FOURCC API proposal, or new ioctls fo=
r=20
the above two operations ?

--=20
Regards,

Laurent Pinchart