[PATCH 09/64] drm/simple: Introduce drmm_simple_encoder_init

[Thomas Zimmermann]

Hi

Am 20.06.22 um 16:39 schrieb Maxime Ripard:
> On Mon, Jun 20, 2022 at 04:25:38PM +0200, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 20.06.22 um 15:48 schrieb Maxime Ripard:
>>> Hi,
>>>
>>> On Mon, Jun 20, 2022 at 12:44:24PM +0200, Thomas Zimmermann wrote:
>>>> Am 10.06.22 um 11:28 schrieb Maxime Ripard:
>>>>> The DRM-managed function to register an encoder is
>>>>> drmm_simple_encoder_alloc() and its variants, which will allocate the
>>>>> underlying structure and initialisation the encoder.
>>>>>
>>>>> However, we might want to separate the structure creation and the encoder
>>>>> initialisation, for example if the structure is shared across multiple DRM
>>>>> entities, for example an encoder and a connector.
>>>>>
>>>>> Let's create an helper to only initialise an encoder that would be passed
>>>>> as an argument.
>>>>>
>>>>
>>>> There's nothing wrong with this patch, but I have to admit that adding
>>>> drm_simple_encoder_init() et al was a mistake.
>>>
>>> Why do you think it was a mistake?
>>
>> The simple-encoder stuff is an interface that no one really needs. Compared
>> to open-coding the function, it's barely an improvement in LOCs, but nothing
>> else.
>>
>> Back when I added drm_simple_encoder_init(), I wanted to simplify the many
>> drivers that initialized the encoder with a cleanup callback and nothing
>> else.  IIRC it was an improvement back then.  But now we already have a
>> related drmm_ helper and a drmm_alloc_ helper. If I had only added the macro
>> back then, we could use the regular encoder helpers.
>>
>>>
>>>> It would have been better to add an initializer macro like
>>>>
>>>> #define DRM_STATIC_ENCODER_DEFAULT_FUNCS \
>>>>     .destroy = drm_encoder_cleanup
>>>>
>>>> It's way more flexible and similarly easy to use. Anyway...
>>>
>>> We can still have this. It would simplify this series so I could
>>> definitely squeeze that patch in and add a TODO item / deprecation
>>> notice for simple encoders if you think it's needed
>>
>> Not necessary. It's not super important.
> 
> The corollary is though :)
> 
> If I understand you right, it means that you'd rather have a destroy
> callback everywhere instead of calling the _cleanup function through a
> drm-managed callback, and let drm_dev_unregister do its job?
> 
> If so, it means that we shouldn't be following the drmm_.*_alloc
> functions and should drop all the new ones from this series.

No, no. What I'm saying is that simple-encoder is a pointless mid-layer. 
There's nothing that couldn't easily be achieved with the regular 
encoder functions.

Best regards
Thomas

> 
> Maxime

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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