On Wed, Nov 27, 2013 at 09:04:38AM -0800, Jesse Barnes wrote:
> On Thu, 14 Nov 2013 02:00:00 +0200
> ville.syrj...@linux.intel.com wrote:
> 
> > From: Ville Syrjälä <ville.syrj...@linux.intel.com>
> > 
> > On VLV the GTFIFOCTL register has other bits besides the number of free
> > entries in the GT wake FIFO. Apply a mask when we read th register to
> > make sure we don't misinterpret the number of free FIFO entries.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h     | 3 ++-
> >  drivers/gpu/drm/i915/intel_uncore.c | 6 +++---
> >  2 files changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> > b/drivers/gpu/drm/i915/i915_reg.h
> > index e8f47de..e243105 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -4860,7 +4860,8 @@
> >  #define    GT_FIFO_IAWRERR                 (1<<1)
> >  #define    GT_FIFO_IARDERR                 (1<<0)
> >  
> > -#define  GT_FIFO_FREE_ENTRIES                      0x120008
> > +#define  GTFIFOCTL                         0x120008
> > +#define    GT_FIFO_FREE_ENTRIES_MASK               0x7f
> >  #define    GT_FIFO_NUM_RESERVED_ENTRIES            20
> >  
> >  #define  HSW_IDICR                         0x9008
> > diff --git a/drivers/gpu/drm/i915/intel_uncore.c 
> > b/drivers/gpu/drm/i915/intel_uncore.c
> > index a9849ab..71902c4 100644
> > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > @@ -148,10 +148,10 @@ static int __gen6_gt_wait_for_fifo(struct 
> > drm_i915_private *dev_priv)
> >  
> >     if (dev_priv->uncore.fifo_count < GT_FIFO_NUM_RESERVED_ENTRIES) {
> >             int loop = 500;
> > -           u32 fifo = __raw_i915_read32(dev_priv, GT_FIFO_FREE_ENTRIES);
> > +           u32 fifo = __raw_i915_read32(dev_priv, GTFIFOCTL) & 
> > GT_FIFO_FREE_ENTRIES_MASK;
> >             while (fifo <= GT_FIFO_NUM_RESERVED_ENTRIES && loop--) {
> >                     udelay(10);
> > -                   fifo = __raw_i915_read32(dev_priv, 
> > GT_FIFO_FREE_ENTRIES);
> > +                   fifo = __raw_i915_read32(dev_priv, GTFIFOCTL) & 
> > GT_FIFO_FREE_ENTRIES_MASK;
> >             }
> >             if (WARN_ON(loop < 0 && fifo <= GT_FIFO_NUM_RESERVED_ENTRIES))
> >                     ++ret;
> > @@ -806,7 +806,7 @@ static int gen6_do_reset(struct drm_device *dev)
> >             dev_priv->uncore.funcs.force_wake_put(dev_priv);
> >  
> >     /* Restore fifo count */
> > -   dev_priv->uncore.fifo_count = __raw_i915_read32(dev_priv, 
> > GT_FIFO_FREE_ENTRIES);
> > +   dev_priv->uncore.fifo_count = __raw_i915_read32(dev_priv, GTFIFOCTL) & 
> > GT_FIFO_FREE_ENTRIES_MASK;
> >  
> >     spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
> >     return ret;
> 
> I don't see this reg on HSW, but it looks like our HSW code uses this
> routine?
> 
> Assuming the spec is just broken today... at least I see it for other
> gens.
> 
> Reviewed-by: Jesse Barnes <jbar...@virtuousgeek.org>

Both merged with a little note about this one here. We can back it out
again ;-)

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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