2016-09-22 Christian König <christian.koenig at amd.com>: > Am 22.09.2016 um 13:16 schrieb Gustavo Padovan: > > 2016-09-22 Christian König <christian.koenig at amd.com>: > > > > > Dropping the rest of the patch, cause that really doesn't make sense any > > > more. > > > > > > Am 22.09.2016 um 12:40 schrieb Gustavo Padovan: > > > > > E.g. for example it is illegal to do something like > > > > > > "while(!fence_is_signaled(f)) sleep();" without enabling signaling > > > > > > before > > > > > > doing this. > > > > > > > > > > > > Could just be a misunderstanding, but the comments on your patch > > > > > > actually > > > > > > sounds a bit like somebody is trying to do exactly that. > > > > I think the usecase in mind here is poll(fd, timeout=0) > > > Exactly as I feared. Even if userspace polls with timeout=0 you still need > > > to call enable_signaling(). > > > > > > Otherwise you can run into a situation where userspace only uses timeout=0 > > > and so never activates the signaling check in the driver. > > > > > > This would in turn result in an endless loop on implementations where the > > > driver never signals fences on their own. > > Polling is optional, userspace may never call it. And DRM/KMS or GPU > > drivers will be doing fence_wait() themselves so signaling is enabled at > > some point. > > No they won't. We have an use case where we clearly want to avoid that as > much as possible because and so the driver never calls enable_signaling() on > it's own. > > Exposing this poll function to userspace without enabling signaling is a > clear NAK from my side.
Okay. So you are NAK'ing the does_not_pool_wait change. Should we revert that one then? It is already broken. Gustavo
