[Intel-gfx] [PATCH 14/28] drm/i915: disable watermarks on VLV, pondicherry takes care of this

[Ville Syrjälä]

On Wed, Mar 06, 2013 at 08:14:54PM +0100, Daniel Vetter wrote:
> On Wed, Mar 06, 2013 at 09:09:06PM +0200, Ville Syrjälä wrote:
> > On Wed, Mar 06, 2013 at 07:56:33PM +0100, Daniel Vetter wrote:
> > > On Fri, Mar 01, 2013 at 01:14:17PM -0800, Jesse Barnes wrote:
> > > > For current usage, not needed.
> > > > 
> > > > Signed-off-by: Vijay Purushothaman <vijay.a.purushothaman at intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/intel_pm.c |    4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > > > index 7de8cec..b8f5a17 100644
> > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > @@ -4211,7 +4211,9 @@ void intel_init_pm(struct drm_device *dev)
> > > >  		} else
> > > >  			dev_priv->display.update_wm = NULL;
> > > >  	} else if (IS_VALLEYVIEW(dev)) {
> > > > -		dev_priv->display.update_wm = valleyview_update_wm;
> > > > +//		dev_priv->display.update_wm = valleyview_update_wm;
> > > > +		dev_priv->display.update_wm = NULL;
> > > > +//		dev_priv->display.update_sprite_wm = valleyview_update_sprite_wm;
> > > 
> > > Either kill this all (it's kzalloced so no need for NULL assignments) or
> > > add a giant comment explaining what's going on. Adding commented-out code
> > > without comment is strange ...
> > 
> > The whole premise that pondicherry magically handles things is a bit
> > weird too. I suppose all it really means is that the default WMs were
> > high enough to avoid underruns for the guys who tested this.
> > 
> > Actually wasn't there a comment on an earlier version of this patch
> > that there was a div by zero or something, and that's the real reason
> > for this patch?
> 
> Fyi the patch which fixed div-by-zero on other platforms is:
> 
> commit 3490ea5de6ac4af309c3df8a26a5cca61306334c
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Mon Jan 7 10:11:40 2013 +0000
> 
>     drm/i915: Treat crtc->mode.clock == 0 as disabled

Now I actually remember that Jani did try reverting this patch in his
tree, and didn't get any div by zeros. So we were a bit confused about
the patch at the time. If he had that fix in his tree, then that would
explain it. Maybe this patch can be dropped then?

-- 
Ville Syrjälä
Intel OTC