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

[zhoucm1]

this patch series reminder me my another thoughts recently, But I don't 
know if my idea is appropriated:
sometimes one person could only need wait any of these fence array, but 
it doesn't want to call fence_wait_any since which will block its 
thread. if there is a mechanism let the person register a callback to 
these fence array, then that will be very convenient.
So I want to add a event fence, which is a special kind of fence and 
indicates this event is satisfied and is signalled by any of the fence 
array.

What do you think of it?

Regards,
David Zhou

On 2016年03月24日 15:20, Maarten Lankhorst wrote:
> Hey,
>
> Op 23-03-16 om 19:47 schreef Gustavo Padovan:
>> From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
>>
>> Hi,
>>
>> This is a first proposal to discuss the addition of in-fences support
>> to DRM. It adds a new struct to fence.c to abstract the use of sync_file
>> in DRM drivers. The new struct fence_collection contains a array with all
>> fences that a atomic commit needs to wait on
>>
>> /**
>>   * struct fence_collection - aggregate fences together
>>   * @num_fences: number of fence in the collection.
>>   * @user_data: user data.
>>   * @func: user callback to put user data.
>>   * @fences: array of @num_fences fences.
>>   */
>> struct fence_collection {
>>         int num_fences;
>>         void *user_data;
>>         collection_put_func_t func;
>>         struct fence *fences[];
>> };
>>
>>
>> The fence_collection is allocated and filled by sync_file_fences_get() and
>> atomic_commit helpers can use fence_collection_wait() to wait the fences to
>> signal.
>>
>> These patches depends on the sync ABI rework:
>>
>> https://www.spinics.net/lists/dri-devel/msg102795.html
>>
>> and the patch to de-stage the sync framework:
>>
>> https://www.spinics.net/lists/dri-devel/msg102799.html
>>
>>
>> I also hacked together some sync support into modetest for testing:
>>
>> https://git.collabora.com/cgit/user/padovan/libdrm.git/log/?h=atomic
>>
> Why did you choose to add fence_collection, rather than putting sync_file in state?
>
> There used to be a sync_fence_wait function, which would mean you'd have everything you need.
>
> ~Maarten
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