drm/radeon: fix ring free alignment calculations

fd.o bz#21849

We were aligning to +16 dwords, instead of to the next 16dword
boundary in the ring. Fix the calculation to go to the next 16dword
boundary when space checking.

Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_cp.c b/drivers/gpu/drm/radeon/radeon_cp.c
index 77a7a4d84650..aff90bb96488 100644
--- a/drivers/gpu/drm/radeon/radeon_cp.c
+++ b/drivers/gpu/drm/radeon/radeon_cp.c
@@ -2185,9 +2185,9 @@ void radeon_commit_ring(drm_radeon_private_t *dev_priv)
 
         /* check if the ring is padded out to 16-dword alignment */
 
-        tail_aligned = dev_priv->ring.tail & 0xf;
+        tail_aligned = dev_priv->ring.tail & (RADEON_RING_ALIGN-1);
         if (tail_aligned) {
-                int num_p2 = 16 - tail_aligned;
+                int num_p2 = RADEON_RING_ALIGN - tail_aligned;
 
                 ring = dev_priv->ring.start;
                 /* pad with some CP_PACKET2 */
diff --git a/drivers/gpu/drm/radeon/radeon_drv.h b/drivers/gpu/drm/radeon/radeon_drv.h
index 8071d965f142..0c6bfc1de153 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.h
+++ b/drivers/gpu/drm/radeon/radeon_drv.h
@@ -1964,11 +1964,14 @@ do {								\
 
 #define RING_LOCALS     int write, _nr, _align_nr; unsigned int mask; u32 *ring;
 
+#define RADEON_RING_ALIGN 16
+
 #define BEGIN_RING( n ) do {                                            \
         if ( RADEON_VERBOSE ) {                                         \
                 DRM_INFO( "BEGIN_RING( %d )\n", (n));                   \
         }                                                               \
-        _align_nr = (n + 0xf) & ~0xf;                                   \
+        _align_nr = RADEON_RING_ALIGN - ((dev_priv->ring.tail + n) & (RADEON_RING_ALIGN-1));    \
+        _align_nr += n;                                                 \
         if (dev_priv->ring.space <= (_align_nr * sizeof(u32))) {        \
                 COMMIT_RING();                                          \
                 radeon_wait_ring( dev_priv, _align_nr * sizeof(u32));   \