drm/i915: IVB/HSW have 32 fence register

Increase the number of fence registers to 32 on IVB/HSW. VLV however
only has 16 fence registers according to the docs.

Increasing the number of fences was attempted before [1], but there was
some uncertainty about the maximum CPU fence number for FBC. Since then
BSpec has been updated to state that there are in fact 32 fence registers,
and the CPU fence number field in the SNB_DPFC_CTL_SA register is 5 bits,
and the CPU fence number field in the ILK_DPFC_CONTROL register must be
zero. So now it all makes sense.

[1] http://lists.freedesktop.org/archives/intel-gfx/2011-October/012865.html

v2: Include some background information based on the previous attempt

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

3 files changed, 7 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a4a8e608649f..b5a495a97ea7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -195,9 +195,9 @@ struct drm_i915_master_private {
         struct _drm_i915_sarea *sarea_priv;
 };
 #define I915_FENCE_REG_NONE -1
-#define I915_MAX_NUM_FENCES 16
-/* 16 fences + sign bit for FENCE_REG_NONE */
-#define I915_MAX_NUM_FENCE_BITS 5
+#define I915_MAX_NUM_FENCES 32
+/* 32 fences + sign bit for FENCE_REG_NONE */
+#define I915_MAX_NUM_FENCE_BITS 6
 
 struct drm_i915_fence_reg {
         struct list_head lru_list;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index da6d6de0a8b9..6be940effefd 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4190,7 +4190,9 @@ i915_gem_load(struct drm_device *dev)
         if (!drm_core_check_feature(dev, DRIVER_MODESET))
                 dev_priv->fence_reg_start = 3;
 
-        if (INTEL_INFO(dev)->gen >= 4 || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
+        if (INTEL_INFO(dev)->gen >= 7 && !IS_VALLEYVIEW(dev))
+                dev_priv->num_fence_regs = 32;
+        else if (INTEL_INFO(dev)->gen >= 4 || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
                 dev_priv->num_fence_regs = 16;
         else
                 dev_priv->num_fence_regs = 8;
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b4e237d9927d..e97bbb2abd59 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1213,7 +1213,7 @@ static void i915_gem_record_fences(struct drm_device *dev,
         switch (INTEL_INFO(dev)->gen) {
         case 7:
         case 6:
-                for (i = 0; i < 16; i++)
+                for (i = 0; i < dev_priv->num_fence_regs; i++)
                         error->fence[i] = I915_READ64(FENCE_REG_SANDYBRIDGE_0 + (i * 8));
                 break;
         case 5: