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

[Thomas Zimmermann]

Hi

Am 29.09.23 um 09:33 schrieb Geert Uytterhoeven:
> Hi Thomas,
> 
> On Fri, Sep 29, 2023 at 9:11 AM Thomas Zimmermann <tzimmermann at suse.de> wrote:
>> Am 28.09.23 um 17:32 schrieb Geert Uytterhoeven:
>>> On Thu, Sep 28, 2023 at 3:59 PM Thomas Zimmermann <tzimmermann at suse.de> 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.
> 
> To clarify: do you mean keeping the single big drm_modeset_helper_vtables.h,
> or the split drm_*_helper_vtable.h set?

I meant to keep the single big drm_modeset_helper_vtables.h. It's not 
nice to look at, but I think we might easily mess up the header 
dependencies with any changes.

Best regards
Thomas

> 
> Thanks!
> 
>>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
>>>>> ---
>>>>> 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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