From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Widawsky <benjamin.widawsky@linux.intel.com>
Subject: Re: [PATCH] drm/i915/bdw: Add 42ms delay for IPS disable
Date: Thu, 10 Apr 2014 11:41:12 -0700
Message-ID: <20140410184112.GB8164@linux.intel.com>
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To: Chris Wilson <chris@chris-wilson.co.uk>, Ben Widawsky <benjamin.widawsky@intel.com>, Intel GFX <intel-gfx@lists.freedesktop.org>, Art Runyan <arthur.j.runyan@intel.com>
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On Thu, Apr 10, 2014 at 07:12:46PM +0100, Chris Wilson wrote:
> On Thu, Apr 10, 2014 at 11:04:17AM -0700, Ben Widawsky wrote:
> > From: Ben Widawsky <benjamin.widawsky@linux.intel.com>
> > 
> > This is a requirement added to the spec. This patch will present
> > persistent corruption on the display.

s/present/prevent

> 
> Prevent? I don't think we want to start showing corruption to the user.
>  
> > Cc: Art Runyan <arthur.j.runyan@intel.com>
> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 7f02444..ebc84ee 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -3583,7 +3583,7 @@ void hsw_disable_ips(struct intel_crtc *crtc)
> >  		return;
> >  
> >  	assert_plane_enabled(dev_priv, crtc->plane);
> > -	if (IS_BROADWELL(crtc->base.dev)) {
> > +	if (IS_BROADWELL(dev)) {
> >  		mutex_lock(&dev_priv->rps.hw_lock);
> >  		WARN_ON(sandybridge_pcode_write(dev_priv, DISPLAY_IPS_CONTROL, 0));
> >  		mutex_unlock(&dev_priv->rps.hw_lock);
> > @@ -3594,6 +3594,10 @@ void hsw_disable_ips(struct intel_crtc *crtc)
> >  
> >  	/* We need to wait for a vblank before we can disable the plane. */
> >  	intel_wait_for_vblank(dev, crtc->pipe);
> > +
> > +	/* wait for pcode to finish disabling IPS, which may take up to 42ms */
> > +	if (IS_BROADWELL(dev))
> > +		msleep(42);
> 
> Reading too much Douglas Adams?
> -Chris
> 

It's those damn display arTchitects

-- 
Ben Widawsky, Intel Open Source Technology Center