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

From	Gustavo Padovan <gustavo@padovan.org>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support
Date	2016-10-27 16:50 +0200
Message-ID	<swTHc-31G-7@gated-at.bofh.it> (permalink)
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2016-10-27 Brian Starkey <brian.starkey@arm.com>:

> On Wed, Oct 26, 2016 at 07:43:57PM -0200, Gustavo Padovan wrote:
> > 2016-10-26 Brian Starkey <brian.starkey@arm.com>:
> > 
> > > 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@arm.com>
> > > ---
> > >  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.

Maybe we should do something similar to the crtc vblank handlers and
even hide the connector_state. Those helpers only take the crtc.
They are able to hold ref to the event as well.

Gustavo

Thread

[RFC PATCH v2 0/9] Introduce writeback connectors Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:00 +0200
  [RFC PATCH v2 4/9] drm: mali-dp: Add RGB writeback formats for DP550/DP650 Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:00 +0200
  [RFC PATCH v2 3/9] drm: mali-dp: Rename malidp_input_format Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:00 +0200
  [RFC PATCH v2 2/9] drm: mali-dp: Clear CVAL when leaving config mode Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:00 +0200
  [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:10 +0200
    Re: [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support Gustavo Padovan <gustavo@padovan.org> - 2016-10-26 23:50 +0200
      Re: [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support Brian Starkey <brian.starkey@arm.com> - 2016-10-27 16:00 +0200
        Re: [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support Daniel Vetter <daniel@ffwll.ch> - 2016-10-27 16:20 +0200
        Re: [RFC PATCH v2 9/9] drm: mali-dp: Add writeback out-fence support Gustavo Padovan <gustavo@padovan.org> - 2016-10-27 16:50 +0200
  [RFC PATCH v2 5/9] drm: mali-dp: Add support for writeback on DP550/DP650 Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:10 +0200
  [RFC PATCH v2 7/9] drm: atomic: factor out common out-fence operations Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:10 +0200
    Re: [RFC PATCH v2 7/9] drm: atomic: factor out common out-fence  operations Daniel Vetter <daniel@ffwll.ch> - 2016-10-26 13:10 +0200
    Re: [RFC PATCH v2 7/9] drm: atomic: factor out common out-fence  operations Gustavo Padovan <gustavo@padovan.org> - 2016-10-26 23:40 +0200
    Re: [RFC PATCH v2 7/9] drm: atomic: factor out common out-fence  operations Gustavo Padovan <gustavo@padovan.org> - 2016-10-26 23:50 +0200
      Re: [RFC PATCH v2 7/9] drm: atomic: factor out common out-fence  operations Brian Starkey <brian.starkey@arm.com> - 2016-10-27 16:30 +0200
  [RFC PATCH v2 6/9] drm: mali-dp: Add writeback connector Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:10 +0200
  [RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback connectors Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:10 +0200
    Re: [RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback  connectors Daniel Vetter <daniel@ffwll.ch> - 2016-10-26 13:10 +0200
    Re: [RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback  connectors Brian Starkey <brian.starkey@arm.com> - 2016-10-26 14:50 +0200
    Re: [RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback  connectors Gustavo Padovan <gustavo@padovan.org> - 2016-10-26 23:50 +0200
      Re: [RFC PATCH v2 8/9] drm: writeback: Add out-fences for writeback  connectors Brian Starkey <brian.starkey@arm.com> - 2016-10-27 17:00 +0200
  [RFC PATCH v2 1/9] drm: Add writeback connector type Brian Starkey <brian.starkey@arm.com> - 2016-10-26 11:10 +0200
    Re: [RFC PATCH v2 1/9] drm: Add writeback connector type Daniel Vetter <daniel@ffwll.ch> - 2016-10-26 13:10 +0200
      Re: [RFC PATCH v2 1/9] drm: Add writeback connector type Brian Starkey <brian.starkey@arm.com> - 2016-10-26 14:50 +0200
        Re: [RFC PATCH v2 1/9] drm: Add writeback connector type Daniel Vetter <daniel@ffwll.ch> - 2016-10-26 15:10 +0200

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