ttm: Fix caching mode selection.

A bug caused a new caching state to be selected on each buffer object
validation regardless of the current caching state.
Moreover, a caching state could be selected that wasn't supported by
the memory type.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 39 insertions, 12 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index c1c407f7cca3..a753598a5e35 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -655,31 +655,52 @@ retry_pre_get:
         return 0;
 }
 
+static uint32_t ttm_bo_select_caching(struct ttm_mem_type_manager *man,
+                                      uint32_t cur_placement,
+                                      uint32_t proposed_placement)
+{
+        uint32_t caching = proposed_placement & TTM_PL_MASK_CACHING;
+        uint32_t result = proposed_placement & ~TTM_PL_MASK_CACHING;
+
+        /**
+         * Keep current caching if possible.
+         */
+
+        if ((cur_placement & caching) != 0)
+                result |= (cur_placement & caching);
+        else if ((man->default_caching & caching) != 0)
+                result |= man->default_caching;
+        else if ((TTM_PL_FLAG_CACHED & caching) != 0)
+                result |= TTM_PL_FLAG_CACHED;
+        else if ((TTM_PL_FLAG_WC & caching) != 0)
+                result |= TTM_PL_FLAG_WC;
+        else if ((TTM_PL_FLAG_UNCACHED & caching) != 0)
+                result |= TTM_PL_FLAG_UNCACHED;
+
+        return result;
+}
+
+
 static bool ttm_bo_mt_compatible(struct ttm_mem_type_manager *man,
                                  bool disallow_fixed,
                                  uint32_t mem_type,
-                                 uint32_t mask, uint32_t *res_mask)
+                                 uint32_t proposed_placement,
+                                 uint32_t *masked_placement)
 {
         uint32_t cur_flags = ttm_bo_type_flags(mem_type);
 
         if ((man->flags & TTM_MEMTYPE_FLAG_FIXED) && disallow_fixed)
                 return false;
 
-        if ((cur_flags & mask & TTM_PL_MASK_MEM) == 0)
+        if ((cur_flags & proposed_placement & TTM_PL_MASK_MEM) == 0)
                 return false;
 
-        if ((mask & man->available_caching) == 0)
+        if ((proposed_placement & man->available_caching) == 0)
                 return false;
-        if (mask & man->default_caching)
-                cur_flags |= man->default_caching;
-        else if (mask & TTM_PL_FLAG_CACHED)
-                cur_flags |= TTM_PL_FLAG_CACHED;
-        else if (mask & TTM_PL_FLAG_WC)
-                cur_flags |= TTM_PL_FLAG_WC;
-        else
-                cur_flags |= TTM_PL_FLAG_UNCACHED;
 
-        *res_mask = cur_flags;
+        cur_flags |= (proposed_placement & man->available_caching);
+
+        *masked_placement = cur_flags;
         return true;
 }
 
@@ -723,6 +744,9 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
                 if (!type_ok)
                         continue;
 
+                cur_flags = ttm_bo_select_caching(man, bo->mem.placement,
+                                                  cur_flags);
+
                 if (mem_type == TTM_PL_SYSTEM)
                         break;
 
@@ -779,6 +803,9 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
                                           proposed_placement, &cur_flags))
                         continue;
 
+                cur_flags = ttm_bo_select_caching(man, bo->mem.placement,
+                                                  cur_flags);
+
                 ret = ttm_bo_mem_force_space(bdev, mem, mem_type,
                                              interruptible, no_wait);