drm/ttm: Add a parameter to add extra pages into ttm_tt

Add a parameter called "extra_pages" for ttm_tt_init, to indicate that
driver needs extra pages in ttm_tt.

v2:
  Used imperative wording [Thomas and Christian]
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
cc: Christian Koenig <christian.koenig@amd.com>
cc: Hellstrom Thomas <thomas.hellstrom@intel.com>
Reviewed-by: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian Konig <christian.koenig@amd.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220401123751.27771-8-ramalingam.c@intel.com

drivers/gpu/drm/drm_gem_vram_helper.c

@@ -864,7 +864,7 @@ static struct ttm_tt *bo_driver_ttm_tt_create(struct ttm_buffer_object *bo,
 	if (!tt)
 		return NULL;
 
-	ret = ttm_tt_init(tt, bo, page_flags, ttm_cached);
+	ret = ttm_tt_init(tt, bo, page_flags, ttm_cached, 0);
 	if (ret < 0)
 		goto err_ttm_tt_init;
 

drivers/gpu/drm/i915/gem/i915_gem_ttm.c

@@ -270,7 +270,7 @@ static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
 		i915_tt->is_shmem = true;
 	}
 
-	ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags, caching);
+	ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags, caching, 0);
 	if (ret)
 		goto err_free;
 

drivers/gpu/drm/qxl/qxl_ttm.c

@@ -113,7 +113,7 @@ static struct ttm_tt *qxl_ttm_tt_create(struct ttm_buffer_object *bo,
 	ttm = kzalloc(sizeof(struct ttm_tt), GFP_KERNEL);
 	if (ttm == NULL)
 		return NULL;
-	if (ttm_tt_init(ttm, bo, page_flags, ttm_cached)) {
+	if (ttm_tt_init(ttm, bo, page_flags, ttm_cached, 0)) {
 		kfree(ttm);
 		return NULL;
 	}

drivers/gpu/drm/ttm/ttm_agp_backend.c

@@ -134,7 +134,7 @@ struct ttm_tt *ttm_agp_tt_create(struct ttm_buffer_object *bo,
 	agp_be->mem = NULL;
 	agp_be->bridge = bridge;
 
-	if (ttm_tt_init(&agp_be->ttm, bo, page_flags, ttm_write_combined)) {
+	if (ttm_tt_init(&agp_be->ttm, bo, page_flags, ttm_write_combined, 0)) {
 		kfree(agp_be);
 		return NULL;
 	}

drivers/gpu/drm/ttm/ttm_tt.c

@@ -134,9 +134,10 @@ void ttm_tt_destroy(struct ttm_device *bdev, struct ttm_tt *ttm)
 static void ttm_tt_init_fields(struct ttm_tt *ttm,
 			       struct ttm_buffer_object *bo,
 			       uint32_t page_flags,
-			       enum ttm_caching caching)
+			       enum ttm_caching caching,
+			       unsigned long extra_pages)
 {
-	ttm->num_pages = PAGE_ALIGN(bo->base.size) >> PAGE_SHIFT;
+	ttm->num_pages = (PAGE_ALIGN(bo->base.size) >> PAGE_SHIFT) + extra_pages;
 	ttm->caching = ttm_cached;
 	ttm->page_flags = page_flags;
 	ttm->dma_address = NULL;
@@ -146,9 +147,10 @@ static void ttm_tt_init_fields(struct ttm_tt *ttm,
 }
 
 int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
-		uint32_t page_flags, enum ttm_caching caching)
+		uint32_t page_flags, enum ttm_caching caching,
+		unsigned long extra_pages)
 {
-	ttm_tt_init_fields(ttm, bo, page_flags, caching);
+	ttm_tt_init_fields(ttm, bo, page_flags, caching, extra_pages);
 
 	if (ttm_tt_alloc_page_directory(ttm)) {
 		pr_err("Failed allocating page table\n");
@@ -180,7 +182,7 @@ int ttm_sg_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
 {
 	int ret;
 
-	ttm_tt_init_fields(ttm, bo, page_flags, caching);
+	ttm_tt_init_fields(ttm, bo, page_flags, caching, 0);
 
 	if (page_flags & TTM_TT_FLAG_EXTERNAL)
 		ret = ttm_sg_tt_alloc_page_directory(ttm);

drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c

@@ -517,7 +517,7 @@ static struct ttm_tt *vmw_ttm_tt_create(struct ttm_buffer_object *bo,
 				     ttm_cached);
 	else
 		ret = ttm_tt_init(&vmw_be->dma_ttm, bo, page_flags,
-				  ttm_cached);
+				  ttm_cached, 0);
 	if (unlikely(ret != 0))
 		goto out_no_init;
 

include/drm/ttm/ttm_tt.h

@@ -140,6 +140,7 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc);
  * @bo: The buffer object we create the ttm for.
  * @page_flags: Page flags as identified by TTM_TT_FLAG_XX flags.
  * @caching: the desired caching state of the pages
+ * @extra_pages: Extra pages needed for the driver.
  *
  * Create a struct ttm_tt to back data with system memory pages.
  * No pages are actually allocated.
@@ -147,7 +148,8 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc);
  * NULL: Out of memory.
  */
 int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
-		uint32_t page_flags, enum ttm_caching caching);
+		uint32_t page_flags, enum ttm_caching caching,
+		unsigned long extra_pages);
 int ttm_sg_tt_init(struct ttm_tt *ttm_dma, struct ttm_buffer_object *bo,
 		   uint32_t page_flags, enum ttm_caching caching);