drm/radeon/evergreen/btc/fusion: setup hdp to invalidate and flush when asked

This needs to be explicitly set on btc.  It's set by default
on evergreen/fusion, so it fine to just unconditionally enable it for
all chips.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@gmail.com>
diff --git a/drivers/gpu/drm/radeon/evergreend.h b/drivers/gpu/drm/radeon/evergreend.h
index 9453384..75b57e3 100644
--- a/drivers/gpu/drm/radeon/evergreend.h
+++ b/drivers/gpu/drm/radeon/evergreend.h
@@ -64,6 +64,8 @@
 #define GB_BACKEND_MAP  				0x98FC
 #define DMIF_ADDR_CONFIG  				0xBD4
 #define HDP_ADDR_CONFIG  				0x2F48
+#define HDP_MISC_CNTL  					0x2F4C
+#define		HDP_FLUSH_INVALIDATE_CACHE      	(1 << 0)
 
 #define	CC_SYS_RB_BACKEND_DISABLE			0x3F88
 #define	GC_USER_RB_BACKEND_DISABLE			0x9B7C