Re: [PATCH 2/7] drm: add syncobj timeline support v8

[zhoucm1 <zhoucm1-5C7GfCeVMHo@public.gmane.org>]

On 2018年10月17日 18:24, Daniel Vetter wrote:
> On Wed, Oct 17, 2018 at 11:29 AM Koenig, Christian
> <Christian.Koenig@amd.com> wrote:
>> Am 17.10.18 um 11:17 schrieb zhoucm1:
>>> [SNIP]
>>>>>    +struct drm_syncobj_signal_pt {
>>>>> +    struct dma_fence_array *base;
>>>> Out of curiosity, why the pointer and not embedding? base is kinda
>>>> misleading for a pointer.
>>> Yeah, Christian doesn't like signal_pt lifecycle same as fence, so
>>> it's a pointer.
>>> If you don't like 'base' name, I can change it.
>> Well I never said that you can't embed the fence array into the signal_pt.
>>
>> You just need to make sure that we don't affect the drm_syncobj
>> lilecycle as well, e.g. that we don't also need to keep that around.
> I don't see a problem with that, as long as drm_syncobj keeps a
> reference to the fence while it's on the timeline list. Which it
> already does. And embedding would avoid that 2nd separate allocation,
> aside from making base less confusing.
That's indeed my initial implementation for signal_pt/wait_pt with fence 
based, but after long and many discussions, we get current solution, as 
you see, the version is up to v8 :).

For here  why the pointer and not embedding?
Two reasons:
1. their lifecycles are not same.
2. It is a fence array usage, which always needs separate allocation, 
seems which is mandatory.
So it is a pointer.

But the name is historical from initial, and indeed be kinda misleading 
for a pointer, I will change it to fence_array instead in coming v9.

Thanks,
David Zhou

> -Daniel

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