RE: [PATCH v3 8/9] dt-bindings: xlnx: Add VTC and TPG bindings

["Klymenko, Anatoliy" <Anatoliy.Klymenko@amd.com>]

> -----Original Message-----
> From: Conor Dooley <conor@kernel.org>
> Sent: Friday, March 29, 2024 8:47 AM
> To: Klymenko, Anatoliy <Anatoliy.Klymenko@amd.com>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>; Laurent Pinchart
> <laurent.pinchart@ideasonboard.com>; Maarten Lankhorst
> <maarten.lankhorst@linux.intel.com>; Maxime Ripard
> <mripard@kernel.org>; Thomas Zimmermann <tzimmermann@suse.de>;
> David Airlie <airlied@gmail.com>; Daniel Vetter <daniel@ffwll.ch>; Simek,
> Michal <michal.simek@amd.com>; Andrzej Hajda
> <andrzej.hajda@intel.com>; Neil Armstrong <neil.armstrong@linaro.org>;
> Robert Foss <rfoss@kernel.org>; Jonas Karlman <jonas@kwiboo.se>; Jernej
> Skrabec <jernej.skrabec@gmail.com>; Rob Herring <robh+dt@kernel.org>;
> Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Conor Dooley
> <conor+dt@kernel.org>; Mauro Carvalho Chehab <mchehab@kernel.org>;
> Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>; dri-
> devel@lists.freedesktop.org; linux-arm-kernel@lists.infradead.org; linux-
> kernel@vger.kernel.org; devicetree@vger.kernel.org; linux-
> media@vger.kernel.org
> Subject: Re: [PATCH v3 8/9] dt-bindings: xlnx: Add VTC and TPG bindings
> 
> On Fri, Mar 29, 2024 at 12:38:33AM +0000, Klymenko, Anatoliy wrote:
> > Thank you for the feedback.
> > > From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> > > Subject: Re: [PATCH v3 8/9] dt-bindings: xlnx: Add VTC and TPG bindings
> > > On 22/03/2024 20:12, Klymenko, Anatoliy wrote:
> > > >> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> > > >> On 21/03/2024 21:43, Anatoliy Klymenko wrote:
> > > >>> diff --git a/include/dt-bindings/media/media-bus-format.h
> > > >>> b/include/dt-
> > > >> bindings/media/media-bus-format.h
> > > >>> new file mode 100644
> > > >>> index 000000000000..60fc6e11dabc
> > > >>> --- /dev/null
> > > >>> +++ b/include/dt-bindings/media/media-bus-format.h
> > > >>> @@ -0,0 +1,177 @@
> > > >>> +/* SPDX-License-Identifier: (GPL-2.0-only OR MIT) */
> > > >>> +/*
> > > >>> + * Media Bus API header
> > > >>> + *
> > > >>> + * Copyright (C) 2009, Guennadi Liakhovetski
> > > >>> +<g.liakhovetski@gmx.de>
> > > >>> + *
> > > >>> + * This program is free software; you can redistribute it and/or
> > > >>> +modify
> > > >>> + * it under the terms of the GNU General Public License version 2
> > > >>> +as
> > > >>> + * published by the Free Software Foundation.
> > > >>
> > > >> That's not true. Your SPDX tells something entirely different.
> > > >>
> > > >
> > > > Thank you - I'll see how to fix it.
> > > >
> > > >> Anyway, you did not explain why you need to copy anything anywhere.
> > > >>
> > > >> Specifically, random hex values *are not bindings*.
> > > >>
> > > >
> > > > The same media bus format values are being used by the reference
> > > > driver in patch #9. And, as far as I know, we cannot use headers from
> > > > Linux API headers directly (at least I
> > >
> > > I don't understand what does it mean. You can use in your driver
> whatever
> > > headers you wish, I don't care about them.
> > >
> > >
> > > noticed the same pattern in ../dt-bindings/sdtv-standarts.h for instance).
> > > What would be the best approach to reusing the same defines on DT and
> > > driver sides from your point of view? Symlink maybe?
> > > >
> > >
> > > Wrap your messages to match mailing list discussion style. There are no
> > > defines used in DT. If there are, show me them in *THIS* or other
> > > *upstreamed* (being upstreamed) patchset.
> > >
> >
> > Sorry, I didn't explain properly what I'm trying to achieve. I need to
> > create a DT node property that represents video signal format, one of
> > MEDIA_BUS_FMT_* from include/uapi/linux/media-bus-format.h. It would
> be
> > nice to reuse the same symbolic values in the device tree. What is the
> > best approach here? Should I create a separate header in
> > include/dt-bindings with the same or similar (to avoid multiple
> > definition errors) defines, or is it better to create a symlink to
> > media-bus-format.h like include/dt-bindings/linux-event-codes.h?
> 
> Isn't there already a property for this, described in
> Documentation/devicetree/bindings/media/xilinx/video.txt
> ?

Those properties are very similar, indeed but not exactly the same. The
one you noticed maps Xilinx video data format on AXI4-Stream transport
that covers color space and chroma subsampling only. The rest of the
signal attributes are either conventional or left out. MEDIA_BUS_FMT_*
collection is more specific and embeds additional information about
video signals, like bits per component and component ordering.