Re: [PATCH 2/2] drm/i915: Fix GT wake FIFO free entries for VLV

Daniel Vetter
2013-11-27T17:15:35Z

On Wed, Nov 27, 2013 at 09:04:38AM -0800, Jesse Barnes wrote:
> On Thu, 14 Nov 2013 02:00:00 +0200
> ville.syrjala@linux.intel.com wrote:
>
> > From: Ville Syrjälä <ville.syrjala@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.syrjala@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 <jbarnes@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