Re: [PATCH 2/9] drm/i915: Warn if drm_vblank_get() still works after drm_vblank_off()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, May 26, 2014 at 03:22:45PM +0200, Daniel Vetter wrote:
> On Mon, May 26, 2014 at 02:46:25PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 3da73ef..da318a7 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -1305,6 +1305,17 @@ static void assert_sprites_disabled(struct drm_i915_private *dev_priv,
> >  	}
> >  }
> >  
> > +static void assert_vblank_disabled(struct intel_crtc *crtc)
> > +{
> > +	struct drm_device *dev = crtc->base.dev;
> > +	enum pipe pipe = crtc->pipe;
> > +
> > +	if (WARN_ON(drm_vblank_get(dev, pipe) == 0)) {
> > +		drm_vblank_put(dev, pipe);
> > +		drm_vblank_off(dev, pipe);
> 
> Imo the _off is too much, since with that it's not just an assert but a
> "... and please make it so if not". Imo better to drop that.

The idea was that if drm_vblank_get() managed to re-enable vblank
interrupts when it wasn't supposed to, we should turn them off again.
But the whole thing is a bug, and another drm_vblank_get() might
happen just after the drm_vblank_off() anyway, so I guess it's a bit
pointless.

> -Daniel
> 
> > +	}
> > +}
> > +
> >  static void ibx_assert_pch_refclk_enabled(struct drm_i915_private *dev_priv)
> >  {
> >  	u32 val;
> > @@ -3885,6 +3896,8 @@ static void intel_crtc_enable_planes(struct drm_crtc *crtc)
> >  	int pipe = intel_crtc->pipe;
> >  	int plane = intel_crtc->plane;
> >  
> > +	assert_vblank_disabled(intel_crtc);
> > +
> >  	intel_enable_primary_hw_plane(dev_priv, plane, pipe);
> >  	intel_enable_planes(crtc);
> >  	/* The fixup needs to happen before cursor is enabled */
> > @@ -3921,6 +3934,8 @@ static void intel_crtc_disable_planes(struct drm_crtc *crtc)
> >  	intel_crtc_update_cursor(crtc, false);
> >  	intel_disable_planes(crtc);
> >  	intel_disable_primary_hw_plane(dev_priv, plane, pipe);
> > +
> > +	assert_vblank_disabled(intel_crtc);
> >  }
> >  
> >  static void ironlake_crtc_enable(struct drm_crtc *crtc)
> > -- 
> > 1.8.5.5
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC