[Intel-gfx] [PATCH] drm/i915: Wait for vblank in i9xx_disable_crtc() for gen 2 only

[Daniel Vetter]

On Wed, Feb 17, 2016 at 11:25:49AM +0200, Jani Nikula wrote:
> On Tue, 16 Feb 2016, Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com> wrote:
> > The wait for other gens was added in commit 564ed191f5d8 ("drm/i915:
> > gmch: fix stuck primary plane due to memory self-refresh mode") since
> > that's necessary when disabling cxsr. However, cxsr disabling was later
> > moved to intel_pre_disable_primary() in commit 87d4300a7dbc ("drm/i915:
> > Move intel_(pre_disable/post_enable)_primary to intel_display.c, and use
> > it there.") and that function got its own vblank wait for cxsr in commit
> > 262cd2e154c2 ("drm/i915: CHV DDR DVFS support and another watermark
> > rewrite"). So remove the extra vblank wait from i9xx_crtc_distable().
> >
> > Cc: Kalyan Kondapally <kalyan.kondapally at intel.com>
> > Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
> 
> Cc: fixes or stable? Fixes which commit exactly of all those?

Why do we want to put a fix to remove a harmless roughly 16ms delay to
stable? Or do I miss something here?
-Daniel

> 
> BR,
> Jani.
> 
> 
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 568eefc..3cb9383 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -6317,10 +6317,9 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
> >  	/*
> >  	 * On gen2 planes are double buffered but the pipe isn't, so we must
> >  	 * wait for planes to fully turn off before disabling the pipe.
> > -	 * We also need to wait on all gmch platforms because of the
> > -	 * self-refresh mode constraint explained above.
> >  	 */
> > -	intel_wait_for_vblank(dev, pipe);
> > +	if (IS_GEN2(dev))
> > +		intel_wait_for_vblank(dev, pipe);
> >  
> >  	for_each_encoder_on_crtc(dev, crtc, encoder)
> >  		encoder->disable(encoder);
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
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> Intel-gfx at lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch