drm/i915: Introduce i915_gem_set_seqno()

This function can be used to set the driver's next_seqno
to arbitrary value.

i915_gem_set_seqno() will idle the gpu, retire outstanding
requests, clear the semaphore mailboxes and set the hardware
status page's seqno index.

Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 29 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bb38bca02559..23b883a135db 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1926,7 +1926,7 @@ i915_gem_object_move_to_inactive(struct drm_i915_gem_object *obj)
 }
 
 static int
-i915_gem_handle_seqno_wrap(struct drm_device *dev)
+i915_gem_init_seqno(struct drm_device *dev, u32 seqno)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
         struct intel_ring_buffer *ring;
@@ -1942,7 +1942,7 @@ i915_gem_handle_seqno_wrap(struct drm_device *dev)
 
         /* Finally reset hw state */
         for_each_ring(ring, dev_priv, i) {
-                intel_ring_init_seqno(ring, 0);
+                intel_ring_init_seqno(ring, seqno);
 
                 for (j = 0; j < ARRAY_SIZE(ring->sync_seqno); j++)
                         ring->sync_seqno[j] = 0;
@@ -1951,6 +1951,32 @@ i915_gem_handle_seqno_wrap(struct drm_device *dev)
         return 0;
 }
 
+int i915_gem_set_seqno(struct drm_device *dev, u32 seqno)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        int ret;
+
+        if (seqno == 0)
+                return -EINVAL;
+
+        /* HWS page needs to be set less than what we
+         * will inject to ring
+         */
+        ret = i915_gem_init_seqno(dev, seqno - 1);
+        if (ret)
+                return ret;
+
+        /* Carefully set the last_seqno value so that wrap
+         * detection still works
+         */
+        dev_priv->next_seqno = seqno;
+        dev_priv->last_seqno = seqno - 1;
+        if (dev_priv->last_seqno == 0)
+                dev_priv->last_seqno--;
+
+        return 0;
+}
+
 int
 i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
 {
@@ -1958,7 +1984,7 @@ i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
 
         /* reserve 0 for non-seqno */
         if (dev_priv->next_seqno == 0) {
-                int ret = i915_gem_handle_seqno_wrap(dev);
+                int ret = i915_gem_init_seqno(dev, 0);
                 if (ret)
                         return ret;