Re: [PATCH 15/35] drm/i915: Print the watermark latencies during init

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

On Tue, Jul 30, 2013 at 06:49:27PM -0300, Paulo Zanoni wrote:
> 2013/7/5  <ville.syrjala@linux.intel.com>:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Seeing the watermark latency values in dmesg might help sometimes.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 25 +++++++++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 37919df..5687957 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -2392,6 +2392,24 @@ static void intel_fixup_cur_wm_latency(struct drm_device *dev, uint16_t wm[5])
> >                 wm[3] *= 2;
> >  }
> >
> > +static void intel_print_wm_latency(struct drm_device *dev, const uint16_t wm[5])
> > +{
> > +       int level;
> > +
> > +       for (level = 0; level <= 4; level++) {
> > +               unsigned int latency = wm[level];
> > +
> > +               if (latency == 0)
> > +                       continue;
> 
> One of the cases that should be interesting to print is exactly when a
> latency we expect to be non-zero is zero. Maybe you should do a simple
> "switch" statement to get max_level depending on Gen number and print
> everything from level 0 to max_level? Then if "latency == 0" we could
> even promote the message to a DRM_ERROR?

Yeah could be done. OTOH if it really happens in the wild, we'd probably
be looking at a bunch of new bug reports that we can't do anything
about.

> > +
> > +               if (level > 0)
> > +                       latency *= 5;
> > +
> > +               DRM_DEBUG_KMS(" WM%d latency %u (%u.%u usec)\n",
> > +                             level, wm[level], latency / 10, latency % 10);
> > +       }
> > +}
> > +
> >  static void intel_setup_wm_latency(struct drm_device *dev)
> >  {
> >         struct drm_i915_private *dev_priv = dev->dev_private;
> > @@ -2405,6 +2423,13 @@ static void intel_setup_wm_latency(struct drm_device *dev)
> >
> >         intel_fixup_spr_wm_latency(dev, dev_priv->wm.spr_latency);
> >         intel_fixup_cur_wm_latency(dev, dev_priv->wm.cur_latency);
> > +
> > +       DRM_DEBUG_KMS("Primary watermark latencies:\n");
> > +       intel_print_wm_latency(dev, dev_priv->wm.pri_latency);
> > +       DRM_DEBUG_KMS("Sprite watermark latencies:\n");
> > +       intel_print_wm_latency(dev, dev_priv->wm.spr_latency);
> > +       DRM_DEBUG_KMS("Cursor watermark latencies:\n");
> > +       intel_print_wm_latency(dev, dev_priv->wm.cur_latency);
> >  }
> >
> >  static void hsw_compute_wm_parameters(struct drm_device *dev,
> > --
> > 1.8.1.5
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> 
> 
> -- 
> Paulo Zanoni

-- 
Ville Syrjälä
Intel OTC