drm/i915: add set_tail hook in struct intel_ring_buffer

This is prepared for video codec ring buffer on Sandybridge. It is
needed to read/write more than one register to move the tail pointer of
the video codec ring on Sandybridge.

Signed-off-by: Xiang, Haihao <haihao.xiang@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 19 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 178e2cea9835..7debb1972eb2 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -132,6 +132,12 @@ static unsigned int render_ring_get_tail(struct drm_device *dev,
         return I915_READ(PRB0_TAIL) & TAIL_ADDR;
 }
 
+static inline void render_ring_set_tail(struct drm_device *dev, u32 value)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        I915_WRITE(PRB0_TAIL, value);
+}
+
 static unsigned int render_ring_get_active_head(struct drm_device *dev,
                 struct intel_ring_buffer *ring)
 {
@@ -144,8 +150,7 @@ static unsigned int render_ring_get_active_head(struct drm_device *dev,
 static void render_ring_advance_ring(struct drm_device *dev,
                 struct intel_ring_buffer *ring)
 {
-        drm_i915_private_t *dev_priv = dev->dev_private;
-        I915_WRITE(PRB0_TAIL, ring->tail);
+        render_ring_set_tail(dev, ring->tail);
 }
 
 static int init_ring_common(struct drm_device *dev,
@@ -159,7 +164,7 @@ static int init_ring_common(struct drm_device *dev,
         /* Stop the ring if it's running. */
         I915_WRITE(ring->regs.ctl, 0);
         I915_WRITE(ring->regs.head, 0);
-        I915_WRITE(ring->regs.tail, 0);
+        ring->set_tail(dev, 0);
 
         /* Initialize the ring. */
         I915_WRITE(ring->regs.start, obj_priv->gtt_offset);
@@ -400,6 +405,12 @@ static inline unsigned int bsd_ring_get_tail(struct drm_device *dev,
         return I915_READ(BSD_RING_TAIL) & TAIL_ADDR;
 }
 
+static inline void bsd_ring_set_tail(struct drm_device *dev, u32 value)
+{
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        I915_WRITE(BSD_RING_TAIL, value);
+}
+
 static inline unsigned int bsd_ring_get_active_head(struct drm_device *dev,
                 struct intel_ring_buffer *ring)
 {
@@ -410,8 +421,7 @@ static inline unsigned int bsd_ring_get_active_head(struct drm_device *dev,
 static inline void bsd_ring_advance_ring(struct drm_device *dev,
                 struct intel_ring_buffer *ring)
 {
-        drm_i915_private_t *dev_priv = dev->dev_private;
-        I915_WRITE(BSD_RING_TAIL, ring->tail);
+        bsd_ring_set_tail(dev, ring->tail);
 }
 
 static int init_bsd_ring(struct drm_device *dev,
@@ -817,6 +827,7 @@ static struct intel_ring_buffer render_ring = {
         .init                   = init_render_ring,
         .get_head               = render_ring_get_head,
         .get_tail               = render_ring_get_tail,
+        .set_tail               = render_ring_set_tail,
         .get_active_head        = render_ring_get_active_head,
         .advance_ring           = render_ring_advance_ring,
         .flush                  = render_ring_flush,
@@ -855,6 +866,7 @@ static struct intel_ring_buffer bsd_ring = {
         .init                   = init_bsd_ring,
         .get_head               = bsd_ring_get_head,
         .get_tail               = bsd_ring_get_tail,
+        .set_tail               = bsd_ring_set_tail,
         .get_active_head        = bsd_ring_get_active_head,
         .advance_ring           = bsd_ring_advance_ring,
         .flush                  = bsd_ring_flush,
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 5603d6e945e9..7bd571c796ae 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -48,6 +48,8 @@ struct  intel_ring_buffer {
                         struct intel_ring_buffer *ring);
         unsigned int    (*get_tail)(struct drm_device *dev,
                         struct intel_ring_buffer *ring);
+        void            (*set_tail)(struct drm_device *dev,
+                        u32 value);
         unsigned int    (*get_active_head)(struct drm_device *dev,
                         struct intel_ring_buffer *ring);
         void            (*advance_ring)(struct drm_device *dev,