[Mesa-dev] egl/android: fence_fd being forced to -1

[Marathe, Yogesh]

> -----Original Message-----
> From: Eric Engestrom [mailto:eric.engestrom at imgtec.com]
> Sent: Thursday, June 15, 2017 7:30 PM
> To: Marathe, Yogesh <yogesh.marathe at intel.com>
> Cc: mesa-dev at lists.freedesktop.org; Chad Versace
> <chadversary at chromium.org>; Palli, Tapani <tapani.palli at intel.com>
> Subject: Re: [Mesa-dev] egl/android: fence_fd being forced to -1
> 
> On Thursday, 2017-06-15 13:27:06 +0000, Marathe, Yogesh wrote:
> > Hello,
> >
> > I'm tyring to run flatland native app on android. It apparantly fails because of a
> fence issue.
> > while debuging further it is observed that
> > droid_window_enqueue_buffer() is forcing fence_fd =-1.
> 
> I assume you've read the comment on the line above the one you mentioned?

Yes I read this, although what's not clear to me is the case that not covered
in comments i.e. when a valid fd needs to be used. I will wait for Chad's comments.
Thanks Eric.

> 
>    /* Queue the buffer without a sync fence. This informs the ANativeWindow
>     * that it may access the buffer immediately.
>     *
>     * From ANativeWindow::dequeueBuffer:
>     *
>     *    The fenceFd argument specifies a libsync fence file descriptor for
>     *    a fence that must signal before the buffer can be accessed.  If
>     *    the buffer can be accessed immediately then a value of -1 should
>     *    be used.  The caller must not use the file descriptor after it
>     *    is passed to queueBuffer, and the ANativeWindow implementation
>     *    is responsible for closing it.
>     */
>    int fence_fd = -1;
>    dri2_surf->window->queueBuffer(dri2_surf->window, dri2_surf->buffer,
>                                   fence_fd);
> 
> > Whats the expectation here if app wants to use fence sync?
> >
> > If we want to have this native app working with the lib where exactly
> > fence should be created / populated, it should be with buffer producer, right?
> 
> I don't know this code personally, so I Cc'ed Chad, who wrote this code in
> commit bfe28b8d93 (albeit 5 years ago, so he might not remember all of it) and
> Tapani who reviewed it.

Yeah this app also seems to be around since then.

> 
> >
> > BTW, We can't/ don't want to change the flatland app!
> >
> > Regards,
> > Yogesh.
> >