From: Daniel Vetter <daniel@ffwll.ch>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm: Don't zero vblank timestamps from the irq handler
Date: Thu, 1 Oct 2015 09:50:16 +0200 [thread overview]
Message-ID: <20151001075016.GP3383@phenom.ffwll.local> (raw)
In-Reply-To: <20151001072720.GA3070@ulmo>
On Thu, Oct 01, 2015 at 09:27:20AM +0200, Thierry Reding wrote:
> On Wed, Sep 30, 2015 at 07:21:34PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > If we couldn't get a high precisions vblank timestamp, we currently
> > store a zeroed timestamp instead and assume the next vblank irq to
> > get us something better. This makes sense when trying to update the
> > timestamp from eg. vblank enable. But if we do this from the vblank
> > irq we will never get a vblank timestamp unless we high precision
> > timestamps are available and succeeded. This break weston for instance
> > on drivers lacking high precision timestamps.
> >
> > To fix this, zero the timestamp only when not called from vbl irq.
> > When called from the irq, we still want the timestamp, even if not
> > perfect.
> >
> > This fixes a regression from
> > 4dfd64862ff852df drm: Use vblank timestamps to guesstimate how many vblanks were missed
> >
> > Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
> > Cc: Thierry Reding <thierry.reding@gmail.com>
> > Reported-by: Thierry Reding <thierry.reding@gmail.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> > drivers/gpu/drm/drm_irq.c | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
>
> Applied on top of next-20151001 and the weston problem I was seeing is
> gone, so:
>
> Tested-by: Thierry Reding <treding@nvidia.com>
>
> I think it might be worth considering squashing this into the offending
> commit to avoid breaking bisectibility.
Can't squash any more since history is frozen in drm-next. Applied to
drm-misc, thanks.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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prev parent reply other threads:[~2015-10-01 7:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-30 16:21 [PATCH] drm: Don't zero vblank timestamps from the irq handler ville.syrjala
2015-10-01 7:27 ` Thierry Reding
2015-10-01 7:50 ` Daniel Vetter [this message]
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