Hi Inki, On 31 March 2016 at 12:26, Inki Dae <daeinki at gmail.com> wrote: > 2016-03-31 19:56 GMT+09:00 Daniel Stone <daniel at fooishbar.org>: >> On 31 March 2016 at 11:05, Inki Dae <inki.dae at samsung.com> wrote: >>> 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.
Yes, absolutely. Implicit fencing is already part of userspace ABI that we can effectively never remove: it would break everyone's desktops on Intel alone, as well as many others. So explicit will be opt-in from the user and the driver both, and only when the combination is fully supported will explicit fencing be used. Cheers, Daniel
