Re: [RFC 0/6] drm/fences: add in-fences to DRM

Inki Dae
2016-03-31T11:27:30Z

Hi Daniel,

2016-03-31 19:56 GMT+09:00 Daniel Stone <daniel@fooishbar.org>:
> Hi Inki,
>
> On 31 March 2016 at 11:05, Inki Dae <inki.dae@samsung.com> wrote:
>> 2016년 03월 31일 18:35에 Daniel Stone 이(가) 쓴 글:
>>> On 31 March 2016 at 08:45, Inki Dae <inki.dae@samsung.com> wrote:
>>>> As of now, it seems that this wouldn't be optional but mandatory if explicit fence support is added to the atomic helper framework. This would definitely be duplication and it seems not clear enough even if one of them is just skipped in runtime.
>>>
>>> Drivers would have to opt in to explicit fencing support, and part of
>>> that would be ensuring that the driver does not wait on implicit
>>> fences when the user has requested explicit fencing be used.
>>>
>>
>> Then, existing drivers would need additional works for explicit fencing support. This wouldn't be really what the drivers have to but should be handled with this patch series because this would affect exising device drivers which use implicit fencing.
>
> Well, yes. Anyone implementing their own atomic commit would need to
> ensure that the commit works properly for fences. The helpers could
> also add it, but the helpers are not mandatory, and you are not
> required to use every part of the helper to use one part of the
> helper. There is no magic wand you can wave that instantly makes it
> work for every driver

I meant there are already several DRM drivers which work properly for
implicit fence. So if atomic helper framework of DRM core is
considered only for the explicit fence, then fencing operation would
affect the existing DRM drivers. So I hope this trying could consider
existing implicit fence users.

Thanks,
Inki Dae
.
>
> Cheers,
> Daniel
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