drm/buddy: stop using PAGE_SIZE

The drm_buddy minimum page-size requirements should be distinct from the
CPU PAGE_SIZE. Only restriction is that the minimum page-size is at
least 4K.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240229105112.250077-3-matthew.auld@intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>

Author: matt-auld

drivers/gpu/drm/drm_buddy.c

@@ -102,7 +102,7 @@ int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size)
 	if (size < chunk_size)
 		return -EINVAL;
 
-	if (chunk_size < PAGE_SIZE)
+	if (chunk_size < SZ_4K)
 		return -EINVAL;
 
 	if (!is_power_of_2(chunk_size))

include/drm/drm_buddy.h

@@ -53,8 +53,8 @@ struct drm_buddy_block {
 	struct list_head tmp_link;
 };
 
-/* Order-zero must be at least PAGE_SIZE */
-#define DRM_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
+/* Order-zero must be at least SZ_4K */
+#define DRM_BUDDY_MAX_ORDER (63 - 12)
 
 /*
  * Binary Buddy System.
@@ -82,7 +82,7 @@ struct drm_buddy {
 	unsigned int n_roots;
 	unsigned int max_order;
 
-	/* Must be at least PAGE_SIZE */
+	/* Must be at least SZ_4K */
 	u64 chunk_size;
 	u64 size;
 	u64 avail;