2016-05-25 Dave Jones <[email protected]>:
> On Sat, May 21, 2016 at 05:31:53AM +0000, Linux Kernel wrote:
>
> > dma-buf/sync_file: de-stage sync_file
> >
> > sync_file is useful to connect one or more fences to the file. The
> file is
> > used by userspace to track fences between drivers that share DMA bufs.
> >
> > Signed-off-by: Gustavo Padovan <[email protected]>
> > Reviewed-by: Daniel Vetter <[email protected]>
> > Signed-off-by: Greg Kroah-Hartman <[email protected]>
>
> ...
>
> > +config SYNC_FILE
> > + bool "sync_file support for fences"
> > + default n
> > + select ANON_INODES
> > + select DMA_SHARED_BUFFER
> > + ---help---
> > + This option enables the fence framework synchronization to export
> > + sync_files to userspace that can represent one or more fences.
>
> For such a generic sounding CONFIG_ item, this is one of the more obtuse
> descriptions
> in a kconfig we've had in a while, and the commit message doesn't give any
> more
> clues as to why anyone might want to enable this.
>
> I'm guessing this is some graphics thing given that Daniel reviewed it.
> From skimming the other commits, it seems to be some Android thing ?
> Are there depends missing perhaps that might make this more obvious ?
You are right, only a few people understand this in the way I wrote. I
definitelly reword this. It is android framework to help userspace with
explict synchronization. DRM will require this, but the patches for that
did not land yet.
Gustavo
