[Intel-gfx] [PATCH 3/3] drm/i915: Re-enable vblank irqs for already active pipes

[Daniel Vetter]

On Tue, May 20, 2014 at 07:31:33PM +0200, Daniel Vetter wrote:
> On Tue, May 20, 2014 at 05:20:05PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > If a pipe is already active when we init/resume there might not be a
> > full modeset afterwards so drm_vblank_on() may not get called. In such
> > a case if someone is holding a vblank reference across a suspend/resume
> > cycle drm_vblank_get() called after resuming won't re-enable the vblank
> > interrupts.
> > 
> > So in order to make sure vblank interrupts get re-enabled post-resume,
> > call drm_vblank_on() in intel_sanitize_crtc() if the crtc is already
> > active.
> > 
> > v2: Also drm_vblank_off() if the pipe got disabled magically
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> This seems to duct-tape over the funny failure I'm seeing on my snb where
> kms_flip/vblank-vs-modeset|dpms-suspend work nicely, but
> kms_flip/vblank-vs-suspend has some totally hilarious random vblank frame
> counter after the modeset.
> 
> Testecase: igt/kms_flip/vblank-vs-suspend
> Tested-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> Now the problem I have: We already call this in the crtc_enable hook. Why
> does calling this here again add the necessary magic?
> 
> /me has no clue

Well, we can figure this out later.

Queued for -next, thanks for the patch.
-Daniel
> 
> Cheers, Daniel
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 9420f4f..2e9f0b0 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -11708,6 +11708,12 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc)
> >  	reg = PIPECONF(crtc->config.cpu_transcoder);
> >  	I915_WRITE(reg, I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);
> >  
> > +	/* restore vblank interrupts to correct state */
> > +	if (crtc->active)
> > +		drm_vblank_on(dev, crtc->pipe);
> > +	else
> > +		drm_vblank_off(dev, crtc->pipe);
> > +
> >  	/* We need to sanitize the plane -> pipe mapping first because this will
> >  	 * disable the crtc (and hence change the state) if it is wrong. Note
> >  	 * that gen4+ has a fixed plane -> pipe mapping.  */
> > -- 
> > 1.8.5.5
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch