Re: [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support

[Brian Starkey]

On Wed, Oct 26, 2016 at 07:43:57PM -0200, Gustavo Padovan wrote:
> 2016-10-26 Brian Starkey <brian.starkey@xxxxxxx>:
>
> > If userspace has asked for an out-fence for the writeback, we add a
> > fence to malidp_mw_job, to be signaled when the writeback job has
> > completed.
> >
> > Signed-off-by: Brian Starkey <brian.starkey@xxxxxxx>
> > ---
> >  drivers/gpu/drm/arm/malidp_hw.c |    5 ++++-
> >  drivers/gpu/drm/arm/malidp_mw.c |   18 +++++++++++++++++-
> >  drivers/gpu/drm/arm/malidp_mw.h |    3 +++
> >  3 files changed, 24 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/arm/malidp_hw.c b/drivers/gpu/drm/arm/malidp_hw.c
> > index 1689547..3032226 100644
> > --- a/drivers/gpu/drm/arm/malidp_hw.c
> > +++ b/drivers/gpu/drm/arm/malidp_hw.c
> > @@ -707,8 +707,11 @@ static irqreturn_t malidp_se_irq(int irq, void *arg)
> >  		unsigned long irqflags;
> >  		/*
> >  		 * We can't unreference the framebuffer here, so we queue it
> > -		 * up on our threaded handler.
> > +		 * up on our threaded handler. However, signal the fence
> > +		 * as soon as possible
> >  		 */
> > +		malidp_mw_job_signal(drm, malidp->current_mw, 0);
>
> Drivers should not deal with fences directly. We need some sort of
> drm_writeback_finished() that will do the signalling for you.

With a signature like this?
	drm_writeback_finished(struct drm_connector_state *state);

I'll have to think about how to achieve that. The state isn't
refcounted and the driver isn't in charge of it's lifetime. I'm not
sure how/where to ensure the state doesn't get destroyed before its
been signaled.

-Brian

> Gustavo