Re: [PATCH] drm/exynos: wait for the completion of pending page flip

[Tomasz Figa <tomasz.figa@gmail.com>]

Hi Inki,

On Wednesday 22 of May 2013 15:37:14 Inki Dae wrote:
> 2013/5/22 Stéphane Marchesin <stephane.marchesin@gmail.com>
> 
> > On Tue, May 21, 2013 at 9:22 PM, Inki Dae <inki.dae@samsung.com> 
wrote:
> > > 2013/5/22 Stéphane Marchesin <stephane.marchesin@gmail.com>
> > > 
> > >> On Tue, May 21, 2013 at 1:08 AM, Inki Dae <inki.dae@samsung.com> 
wrote:
> > >> > This patch fixes the issue that drm_vblank_get() is failed.
> > >> > 
> > >> > The issus occurs when next page flip request is tried
> > >> > if previous page flip event wasn't completed yet and then
> > >> > dpms became off.
> > >> > 
> > >> > So this patch make sure that page flip event is completed
> > >> > before dpms goes to off.
> > >> 
> > >> Hi,
> > >> 
> > >> This patch is a squash of the two following patches from the Chrome
> > >> OS
> > 
> > >> tree with the KDS bits removed and the dpms off bit added:
> > http://git.chromium.org/gitweb/?p=chromiumos/third_party/kernel-next.g
> > it;a=commitdiff;h=2e77cd4e423967862ca01b1af82aa8b5b7429fc4;hp=aba002da
> > 4c6e5efec4d43e1ce33930a79269349a
> > 
> > 
> > http://git.chromium.org/gitweb/?p=chromiumos/third_party/kernel-next.g
> > it;a=commitdiff;h=b4ec8bfa750ef43a43c2da746c8afdbb51002882;hp=4f28b9a7
> > 5c928f229443d7c6c3163159ceb6903a> 
> > >> Please keep proper attribution.
> > > 
> > > Those patches are just for Chrome OS. Please post them if you want
> > > for
> > 
> > those
> > 
> > > to be considered so that they can be reviewed.
> > 
> > We intend to, once they are rebased onto latest kernel. But what I'm
> > pointing out is that you're removing proper attribution from Chrome OS
> > patches, and this is the second time it has happened.
> 
> What is mean? does mainline kernel have the attribution? if not so, we
> don't need to consider it. And please know that I can not be aware of
> you have such patch set without any posting.
> 

at·tri·bu·tion 
n.
1. The act of attributing, especially the act of establishing a particular 
person as the creator of a work of art
[1]

So yes, mainline kernel has attribution. Actually posting something as 
work of someone that is not the author of the posted work is considered 
bad everywhere, isn't it?

However looking at those two patches linked by Stéphane, I'm not really 
sure this patch is really just a squash of them. Stéphane, are you 100% 
sure that your claims are true?

Best regards,
Tomasz

[1] http://www.thefreedictionary.com/attribution

> > > That is why we attend open
> > > source. One more comment, please do not abuse
> > > exynos_drm_crtc_page_flip()> 
> > What do you mean by abuse?
> > 
> > >> Signed-off-by: Inki Dae <inki.dae@samsung.com>
> > >> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> > >> ---
> > >> 
> > >>  drivers/gpu/drm/exynos/exynos_drm_crtc.c |   16 ++++++++++++++++
> > >>  1 files changed, 16 insertions(+), 0 deletions(-)
> > >> 
> > >> diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> > >> b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> > >> index e8894bc..69a77e9 100644
> > >> --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> > >> +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c
> > >> @@ -48,6 +48,8 @@ struct exynos_drm_crtc {
> > >> 
> > >>         unsigned int                    pipe;
> > >>         unsigned int                    dpms;
> > >>         enum exynos_crtc_mode           mode;
> > >> 
> > >> +       wait_queue_head_t               pending_flip_queue;
> > >> +       atomic_t                        pending_flip;
> > >> 
> > >>  };
> > >>  
> > >>  static void exynos_drm_crtc_dpms(struct drm_crtc *crtc, int mode)
> > >> 
> > >> @@ -61,6 +63,13 @@ static void exynos_drm_crtc_dpms(struct drm_crtc
> > 
> > *crtc,
> > 
> > >> int mode)
> > >> 
> > >>                 return;
> > >>         
> > >>         }
> > >> 
> > >> +       if (mode > DRM_MODE_DPMS_ON) {
> > >> +               /* wait for the completion of page flip. */
> > >> +               wait_event(exynos_crtc->pending_flip_queue,
> > >> +                              
> > >> atomic_read(&exynos_crtc->pending_flip)
> > 
> > ==
> > 
> > >> 0);
> > >> +               drm_vblank_off(crtc->dev, exynos_crtc->pipe);
> > >> 
> > >> You should be using vblank_put/get.
> > > 
> > > No, drm_vblank_put should be called by
> > > exynos_drm_crtc_finish_pageflip(). And know that this patch makes
> > > sure that pended page flip event is> 
> > completed
> > 
> > > before dpms goes to off.
> > 
> > You need to do vblank_put/get while you're waiting. Otherwise you
> > don't know for sure that flips will happen. This is especially bad as
> > you don't use a timeout.
> 
> Understood. Right, drm_vblank_get call before wait_event and
> drm_vblank_put call after wait_event.
> 
> Thanks,
> Inki Dae
> 
> > Stéphane
> > 
> > > Thanks,
> > > Inki Dae
> > > 
> > >> Stéphane
> > >> 
> > >> > +       }
> > >> > +
> > >> > 
> > >> >         exynos_drm_fn_encoder(crtc, &mode,
> > >> > 
> > >> > exynos_drm_encoder_crtc_dpms);
> > >> > 
> > >> >         exynos_crtc->dpms = mode;
> > >> >  
> > >> >  }
> > >> > 
> > >> > @@ -225,6 +234,7 @@ static int exynos_drm_crtc_page_flip(struct
> > 
> > drm_crtc
> > 
> > >> > *crtc,
> > >> > 
> > >> >                 spin_lock_irq(&dev->event_lock);
> > >> >                 list_add_tail(&event->base.link,
> > >> >                 
> > >> >                                 &dev_priv->pageflip_event_list);
> > >> > 
> > >> > +               atomic_set(&exynos_crtc->pending_flip, 1);
> > >> > 
> > >> >                 spin_unlock_irq(&dev->event_lock);
> > >> >                 
> > >> >                 crtc->fb = fb;
> > >> > 
> > >> > @@ -344,6 +354,8 @@ int exynos_drm_crtc_create(struct drm_device
> > >> > *dev,
> > >> > unsigned int nr)
> > >> > 
> > >> >         exynos_crtc->pipe = nr;
> > >> >         exynos_crtc->dpms = DRM_MODE_DPMS_OFF;
> > >> > 
> > >> > +       init_waitqueue_head(&exynos_crtc->pending_flip_queue);
> > >> > +       atomic_set(&exynos_crtc->pending_flip, 0);
> > >> > 
> > >> >         exynos_crtc->plane = exynos_plane_init(dev, 1 << nr,
> > >> >         true);
> > >> >         if (!exynos_crtc->plane) {
> > >> >         
> > >> >                 kfree(exynos_crtc);
> > >> > 
> > >> > @@ -398,6 +410,8 @@ void exynos_drm_crtc_finish_pageflip(struct
> > >> > drm_device *dev, int crtc)
> > >> > 
> > >> >  {
> > >> >  
> > >> >         struct exynos_drm_private *dev_priv = dev->dev_private;
> > >> >         struct drm_pending_vblank_event *e, *t;
> > >> > 
> > >> > +       struct drm_crtc *drm_crtc = dev_priv->crtc[crtc];
> > >> > +       struct exynos_drm_crtc *exynos_crtc =
> > 
> > to_exynos_crtc(drm_crtc);
> > 
> > >> >         struct timeval now;
> > >> >         unsigned long flags;
> > >> > 
> > >> > @@ -419,6 +433,8 @@ void exynos_drm_crtc_finish_pageflip(struct
> > >> > drm_device *dev, int crtc)
> > >> > 
> > >> >                 list_move_tail(&e->base.link,
> > >> > 
> > >> > &e->base.file_priv->event_list);
> > >> > 
> > >> >                 wake_up_interruptible(&e->base.file_priv->event_w
> > >> >                 ait);
> > >> >                 drm_vblank_put(dev, crtc);
> > >> > 
> > >> > +               atomic_set(&exynos_crtc->pending_flip, 0);
> > >> > +               wake_up(&exynos_crtc->pending_flip_queue);
> > >> > 
> > >> >         }
> > >> >         
> > >> >         spin_unlock_irqrestore(&dev->event_lock, flags);
> > >> > 
> > >> > --
> > >> > 1.7.5.4
> > >> > 
> > >> > _______________________________________________
> > >> > dri-devel mailing list
> > >> > dri-devel@lists.freedesktop.org
> > >> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
> > >> 
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> > 
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