Re: [PATCH/RFC 3/3] drm: Split drm_modeset_helper_vtables.h

[Thomas Zimmermann]

Hi

Am 28.09.23 um 17:32 schrieb Geert Uytterhoeven:
> Hi Thomas,
>
> On Thu, Sep 28, 2023 at 3:59 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
> > Am 28.09.23 um 14:16 schrieb Geert Uytterhoeven:
> > > <drm/drm_modeset_helper_vtables.h> is the second largest header file in
> > > the DRM subsystem, and declares helpers vtables for various DRM
> > > components.  Several vtables contain methods with the same name, and all
> > > but one vtable do not fit on the screen, making it hard to navigate to
> > > the actual method one is interested in.
> > >
> > > Make it easier for the casual reviewer to keep track by splitting
> > > <drm/drm_modeset_helper_vtables.h> in multiple header files, one per DRM
> > > component.
> >
> > I never liked this header either, but do we need new header files? Each
> > struct could be appended to the end of the regular header: struct
> > drm_plane_helper_funcs to drm_plane.h, drm_connector_helper_func to
> > drm_connector.h and so on.
>
> That would work for me, too.  But perhaps we want to maintain a clear
> separation between core and helpers?
>
> Note that moving the contents to *_helper.h would be another option,
> drm_crtc_helper.h and drm_plane_helper.h already exist.

I've taken a closer look at the users of the _vtables header. There's 
code in drm_atomic_helper.c or drm_probe_helper.c that invokes the 
callback functions.

The drivers fill the pointers with code that often comes from other 
helper modules. That code is in files like drm_plane_helper.c or 
drm_crtc_helper.c. There header files are drm_plane_helper.h, etc.

In that context, the _vtables header makes sense, as it separates the 
callers from the callees. Putting the structs into headers like 
drm_plane_helper.h would move it to the callee side.

I suggest to leave the header as it is. The fallout to the code base 
from refactoring seems worse than the current state.

Best regards
Thomas

> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > > ---
> > > RFC, a future patch could replace inclusion of
> > > <drm/drm_modeset_helper_vtables.h> by inclusion of one or more of the
> > > new files, and reduce compilation time.
> > > ---
> > >    include/drm/drm_connector_helper_vtable.h   |  364 +++++
> > >    include/drm/drm_crtc_helper_vtable.h        |  483 ++++++
> > >    include/drm/drm_encoder_helper_vtable.h     |  381 +++++
> > >    include/drm/drm_mode_config_helper_vtable.h |   97 ++
> > >    include/drm/drm_modeset_helper_vtables.h    | 1466 +------------------
> > >    include/drm/drm_plane_helper_vtable.h       |  297 ++++
> > >    6 files changed, 1627 insertions(+), 1461 deletions(-)
> > >    create mode 100644 include/drm/drm_connector_helper_vtable.h
> > >    create mode 100644 include/drm/drm_crtc_helper_vtable.h
> > >    create mode 100644 include/drm/drm_encoder_helper_vtable.h
> > >    create mode 100644 include/drm/drm_mode_config_helper_vtable.h
> > >    create mode 100644 include/drm/drm_plane_helper_vtable.h
>
> Gr{oetje,eeting}s,
>
>                          Geert

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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