Re: [PATCH 1/2] dt-bindings: media: Add macros for video interface bus types

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

On Sun, Feb 27, 2022 at 11:07:23PM +0200, Sakari Ailus wrote:
> On Sun, Feb 27, 2022 at 10:33:51PM +0200, Laurent Pinchart wrote:
> > Add a new dt-bindings/media/video-interfaces.h header that defines
> > macros corresponding to the bus types from media/video-interfaces.yaml.
> > This allows avoiding hardcoded constants in device tree sources.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  include/dt-bindings/media/video-interfaces.h | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >  create mode 100644 include/dt-bindings/media/video-interfaces.h
> > 
> > diff --git a/include/dt-bindings/media/video-interfaces.h b/include/dt-bindings/media/video-interfaces.h
> > new file mode 100644
> > index 000000000000..e38058e1cca7
> > --- /dev/null
> > +++ b/include/dt-bindings/media/video-interfaces.h
> > @@ -0,0 +1,16 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2022 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > + */
> > +
> > +#ifndef __DT_BINDINGS_MEDIA_VIDEO_INTERFACES_H__
> > +#define __DT_BINDINGS_MEDIA_VIDEO_INTERFACES_H__
> > +
> > +#define MEDIA_BUS_TYPE_CSI2_CPHY		1
> > +#define MEDIA_BUS_TYPE_CSI1			2
> > +#define MEDIA_BUS_TYPE_CCP2			3
> > +#define MEDIA_BUS_TYPE_CSI2_DPHY		4
> > +#define MEDIA_BUS_TYPE_PARALLEL			5
> 
> I've been long thinkin of renaming "PARALLEL" as "BT.601" which it really
> is. I don't mind postponing that, but I think you could as well start here.
> Up to you.

I think it's a good idea, but we then need to decide what to do with
other types of parallel buses. Let's start this discussion now, and
implement it in a patch on top of this series.

> Should this be somehow visible in video-interfaces.yaml?

I wish we could use macros in .yaml files instead of numerical values,
but I don't think that's possible. I can do this:

   bus-type:
     $ref: /schemas/types.yaml#/definitions/uint32
     enum:
-      - 1 # MIPI CSI-2 C-PHY
-      - 2 # MIPI CSI1
-      - 3 # CCP2
-      - 4 # MIPI CSI-2 D-PHY
-      - 5 # Parallel
-      - 6 # BT.656
+      - 1 # MIPI CSI-2 C-PHY (MEDIA_BUS_TYPE_CSI2_CPHY)
+      - 2 # MIPI CSI1 (MEDIA_BUS_TYPE_CSI1)
+      - 3 # CCP2 (MEDIA_BUS_TYPE_CCP2)
+      - 4 # MIPI CSI-2 D-PHY (MEDIA_BUS_TYPE_CSI2_DPHY)
+      - 5 # Parallel (MEDIA_BUS_TYPE_PARALLEL)
+      - 6 # BT.656 (MEDIA_BUS_TYPE_BT656)
     description:
-      Data bus type.
+      Data bus type. Use the macros listed above (defined in
+      dt-bindings/video-interfaces.h) instead of numerical values.

Any better proposal ?

> > +#define MEDIA_BUS_TYPE_BT656			6
> > +
> > +#endif /* __DT_BINDINGS_MEDIA_VIDEO_INTERFACES_H__ */

-- 
Regards,

Laurent Pinchart