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

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Date:	Thu, 24 Mar 2016 08:20:45 +0100
From:	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
To:	Gustavo Padovan <gustavo@...ovan.org>,
	dri-devel@...ts.freedesktop.org
Cc:	linux-kernel@...r.kernel.org, Daniel Stone <daniels@...labora.com>,
	Arve Hjønnevåg <arve@...roid.com>,
	Riley Andrews <riandrews@...roid.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Rob Clark <robdclark@...il.com>,
	Greg Hackmann <ghackmann@...gle.com>,
	John Harrison <John.C.Harrison@...el.com>,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: Re: [RFC 0/6] drm/fences: add in-fences to DRM

Hey,

Op 23-03-16 om 19:47 schreef Gustavo Padovan:
> From: Gustavo Padovan <gustavo.padovan@...labora.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