[PATCH] drm/amdgpu: add ih call to process until checkpoint

[Jonathan Kim]

Add IH function to allow caller to process ring entries until the
checkpoint write pointer.

Suggested-by: Felix Kuehling <felix.kuehling at amd.com>
Signed-off-by: Jonathan Kim <jonathan.kim at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c | 46 +++++++++++++++++++++++++-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h |  2 ++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c
index dc852af4f3b7..cae50af9559d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c
@@ -22,7 +22,7 @@
  */
 
 #include <linux/dma-mapping.h>
-
+#include <linux/processor.h>
 #include "amdgpu.h"
 #include "amdgpu_ih.h"
 
@@ -160,6 +160,50 @@ void amdgpu_ih_ring_write(struct amdgpu_ih_ring *ih, const uint32_t *iv,
 	}
 }
 
+/**
+ * amdgpu_ih_wait_on_checkpoint_process - wait to process IVs up to checkpoint
+ *
+ * @adev: amdgpu_device pointer
+ * @ih: ih ring to process
+ *
+ * Used to ensure ring has processed IVs up to the checkpoint write pointer.
+ */
+int amdgpu_ih_wait_on_checkpoint_process(struct amdgpu_device *adev,
+					struct amdgpu_ih_ring *ih)
+{
+	u32 prev_rptr, cur_rptr, checkpoint_wptr;
+
+	if (!ih->enabled || adev->shutdown)
+		return -ENODEV;
+
+	cur_rptr = READ_ONCE(ih->rptr);
+	/* Order read of current rptr with checktpoint wptr. */
+	mb();
+	checkpoint_wptr = amdgpu_ih_get_wptr(adev, ih);
+
+	/* allow rptr to wrap around  */
+	if (cur_rptr > checkpoint_wptr) {
+		spin_begin();
+		do {
+			spin_cpu_relax();
+			prev_rptr = cur_rptr;
+			cur_rptr = READ_ONCE(ih->rptr);
+		} while (cur_rptr >= prev_rptr);
+		spin_end();
+	}
+
+	/* wait for rptr to catch up to or pass checkpoint. */
+	spin_begin();
+	do {
+		spin_cpu_relax();
+		prev_rptr = cur_rptr;
+		cur_rptr = READ_ONCE(ih->rptr);
+	} while (cur_rptr >= prev_rptr && cur_rptr < checkpoint_wptr);
+	spin_end();
+
+	return 0;
+}
+
 /**
  * amdgpu_ih_process - interrupt handler
  *
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h
index 6ed4a85fc7c3..6817f0a812d2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ih.h
@@ -87,6 +87,8 @@ int amdgpu_ih_ring_init(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih,
 void amdgpu_ih_ring_fini(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih);
 void amdgpu_ih_ring_write(struct amdgpu_ih_ring *ih, const uint32_t *iv,
 			  unsigned int num_dw);
+int amdgpu_ih_wait_on_checkpoint_process(struct amdgpu_device *adev,
+					struct amdgpu_ih_ring *ih);
 int amdgpu_ih_process(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih);
 void amdgpu_ih_decode_iv_helper(struct amdgpu_device *adev,
 				struct amdgpu_ih_ring *ih,
-- 
2.17.1