[PATCH 4.4 213/342] drm: add helper to check for wc memory support

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dave Airlie <airlied@xxxxxxxxxx>

commit 4b0e4e4af6c6dc8354dcb72182d52c1bc55f12fc upstream.

Reviewed-by: Christian KÃnig <christian.koenig@xxxxxxx>
Reviewed-by: Michel DÃnzer <michel.daenzer@xxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Signed-off-by: Oded Gabbay <oded.gabbay@xxxxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

diff --git a/include/drm/drm_cache.h b/include/drm/drm_cache.h
index 7bfb063029d8..461a0558bca4 100644
--- a/include/drm/drm_cache.h
+++ b/include/drm/drm_cache.h
@@ -35,4 +35,13 @@
 
 void drm_clflush_pages(struct page *pages[], unsigned long num_pages);
 
+static inline bool drm_arch_can_wc_memory(void)
+{
+#if defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE)
+	return false;
+#else
+	return true;
+#endif
+}
+
 #endif