[Intel-gfx] [PATCH v2 3/4] drm/i915: Introduce i915_gem_set_seqno()

[Mika Kuoppala]

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.kuopp...@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |    4 ++--
 drivers/gpu/drm/i915/i915_gem.c |   32 +++++++++++++++++++++++++++++---
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 514aee8..b0faa91 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1479,8 +1479,8 @@ i915_seqno_passed(uint32_t seq1, uint32_t seq2)
        return (int32_t)(seq1 - seq2) >= 0;
 }
 
-extern int i915_gem_get_seqno(struct drm_device *dev, u32 *seqno);
-
+int __must_check i915_gem_get_seqno(struct drm_device *dev, u32 *seqno);
+int __must_check i915_gem_set_seqno(struct drm_device *dev, u32 seqno);
 int __must_check i915_gem_object_get_fence(struct drm_i915_gem_object *obj);
 int __must_check i915_gem_object_put_fence(struct drm_i915_gem_object *obj);
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 53442ea..8291896 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;
 
-- 
1.7.9.5

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