[PATCH 2/3] drm/i915: Fix page table entries for Bay Trail.

[Kenneth Graunke <kenneth@whitecape.org>]

On Bay Trail, bit 1 means "writeable by the GPU."  Failing to set that
means basically anything using the GPU will cause hangs.

v2: Drop accidental inline keyword on byt_pte_encode.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com> [v1]
Tested-by: Daniel Leung <daniel.leung@linux.intel.com> [v1]
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

To address Jani's comment about PPGTT - Daniel thinks Jesse has patches
for aliasing PPGTT floating around that could land at some point.  Also,
if we get real PPGTT, we'll also need this.  Either way, setting it up
is trivial and leaving it out could lead to bugs later.

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 92e147f..62058dc 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -73,6 +73,27 @@ static gen6_gtt_pte_t gen6_pte_encode(struct drm_device *dev,
 	return pte;
 }
 
+#define BYT_PTE_WRITEABLE		(1 << 1)
+#define BYT_PTE_SNOOPED_BY_CPU_CACHES	(1 << 2)
+
+static gen6_gtt_pte_t byt_pte_encode(struct drm_device *dev,
+				     dma_addr_t addr,
+				     enum i915_cache_level level)
+{
+	gen6_gtt_pte_t pte = GEN6_PTE_VALID;
+	pte |= GEN6_PTE_ADDR_ENCODE(addr);
+
+	/* Mark the page as writeable.  Other platforms don't have a
+	 * setting for read-only/writable, so this matches that behavior.
+	 */
+	pte |= BYT_PTE_WRITEABLE;
+
+	if (level != I915_CACHE_NONE)
+		pte |= BYT_PTE_SNOOPED_BY_CPU_CACHES;
+
+	return pte;
+}
+
 static int gen6_ppgtt_enable(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
@@ -234,7 +255,11 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	first_pd_entry_in_global_pt =
 		gtt_total_entries(dev_priv->gtt) - I915_PPGTT_PD_ENTRIES;
 
-	ppgtt->pte_encode = gen6_pte_encode;
+	if (IS_VALLEYVIEW(dev)) {
+		ppgtt->pte_encode = byt_pte_encode;
+	} else {
+		ppgtt->pte_encode = gen6_pte_encode;
+	}
 	ppgtt->num_pd_entries = I915_PPGTT_PD_ENTRIES;
 	ppgtt->enable = gen6_ppgtt_enable;
 	ppgtt->clear_range = gen6_ppgtt_clear_range;
@@ -824,7 +849,11 @@ int i915_gem_gtt_init(struct drm_device *dev)
 	} else {
 		dev_priv->gtt.gtt_probe = gen6_gmch_probe;
 		dev_priv->gtt.gtt_remove = gen6_gmch_remove;
-		dev_priv->gtt.pte_encode = gen6_pte_encode;
+		if (IS_VALLEYVIEW(dev)) {
+			dev_priv->gtt.pte_encode = byt_pte_encode;
+		} else {
+			dev_priv->gtt.pte_encode = gen6_pte_encode;
+		}
 	}
 
 	ret = dev_priv->gtt.gtt_probe(dev, &dev_priv->gtt.total,
-- 
1.8.2.1