Re: [PATCH 00/14] drm/i915: Make ILK/SNB/IVB use HSW watermark code

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Dec 05, 2013 at 03:30:33PM +0100, Daniel Vetter wrote:
> On Thu, Dec 5, 2013 at 2:51 PM,  <ville.syrjala@linux.intel.com> wrote:
> > This series still has some underrun issues since the safe watermark
> > update mechanism is yet to be introduced. However it shouldn't really
> > be any worse than what we have ATM, and I'd like to have all the platforms
> > converted so that we have more systems that will excercise the new update
> > mechanism when it arrives.
> 
> How bad are the underrun occurences? I'd really like to make the
> underrun reporting much louder asap ... If it only happens rarely when
> enabling/disabling sprites then I think we should up them to
> DRM_ERROR.

You can also get them when resizing the sprite. But since the current
logic will disable underrun reporting after the first occurence, making
them DRM_ERROR might be OK even now. I have such a patch in my tree
actually.

Once the safe watermark update mechanism is in place, I think we want
to make them even louder. I'm also using a patch that arms a timer to
re-enable the underrun reporting after 2 seconds of it getting disabled.
Although one extra problem is that we still don't properly check the
cdclk related scaling limitations, so it's currently possible to
configure the sprite(s) to cause constant underruns.

-- 
Ville Syrjälä
Intel OTC