From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Subject: Re: [PATCH v2] drm/i915/hsw: Add display Audio codec
 disable sequence for Haswell
Date: Thu, 5 Sep 2013 14:33:20 +0300
Message-ID: <20130905113320.GY11428@intel.com>
References: <1377820220-8251-1-git-send-email-mengdong.lin@intel.com>
	<CAKMK7uEQEdXys-aeeD7Dy_FgLODeAF+fS-_jR_7Ch5_KekZ-Yw@mail.gmail.com>
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To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>, Mukesh <mukeshx.arora@intel.com>
List-Id: intel-gfx@lists.freedesktop.org

On Wed, Sep 04, 2013 at 08:50:13PM +0200, Daniel Vetter wrote:
> On Fri, Aug 30, 2013 at 1:50 AM,  <mengdong.lin@intel.com> wrote:
> > +       /* Wait for 2 vertical blanks */
> > +       intel_wait_for_vblank(dev, pipe);
> > +       intel_wait_for_vblank(dev, pipe);
> > +
> > +       /* Disable audio PD. This is optional as per Bspec.  */
> > +       temp =3D I915_READ(HSW_AUD_PIN_ELD_CP_VLD);
> > +       temp &=3D ~(AUDIO_OUTPUT_ENABLE_A << (pipe * 4));
> > +       I915_WRITE(HSW_AUD_PIN_ELD_CP_VLD, temp);
> =

> If this is optional do we really need the two vblank waits above?
> Adding them just for fun when we generally try to rip out as many
> vblank waits as possible from the modeset code isn't all that great
> ...

One idea I had for these kinds of vblank waits (there also one required
for IPS for instance) is that we might just sample a vblank counter
after the first step, then at the latest point we can, we'd wait for the
frame counter to have passed the sampled vaoue + whatever extra is
needed. That might allow us to do other stuff in parallel while the
required number of vblanks will elapese.

-- =

Ville Syrj=E4l=E4
Intel OTC