drm/radeon/kms: manage r300 CMASK RAM access and allow CMASK clear

The CMASK RAM is for colorbuffer compression (used in conjunction
with MSAA). Only one user (filp) can access it.

The CMASK RAM access is managed in the same way as Hyper-Z, but there is
a separate ioctl, because an app that uses MSAA does not necessarily
have to use zbuffering.

Signed-off-by: Marek Olšák <maraeo@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/radeon_drm.h b/include/drm/radeon_drm.h
index 10f8b53..e95a86b 100644
--- a/include/drm/radeon_drm.h
+++ b/include/drm/radeon_drm.h
@@ -906,6 +906,7 @@
 #define RADEON_INFO_ACCEL_WORKING2	0x05
 #define RADEON_INFO_TILING_CONFIG	0x06
 #define RADEON_INFO_WANT_HYPERZ		0x07
+#define RADEON_INFO_WANT_CMASK		0x08 /* get access to CMASK on r300 */
 
 struct drm_radeon_info {
 	uint32_t		request;