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

Jesse Barnes
2013-11-27T17:09:56Z

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>

--
Jesse Barnes, Intel Open Source Technology Center