From 07dc3d4238e57901ccf98e0b506d9aad2c86b9d9 Mon Sep 17 00:00:00 2001
From: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date: Mon, 10 Jan 2022 17:18:05 -0800
Subject: [PATCH] iris: implement inter-context busy-tracking

Previously, no buffers were ever marked as EXEC_OBJECT_ASYNC so the
Kernel would ensure dependency tracking for us. After we implemented
explicit busy tracking in commit 89a34cb8450a, only the external
objects kept relying on the Kernel's implicit tracking and Iris did
inter-batch busy tracking, meaning we lost inter-screen and
inter-context synchronization. This seemed fine to me since, as far as
I understood, it is the duty of the application to synchronize itself
against multiple screens and contexts.

The problem here is that applications were actually relying on the old
behavior where the Kernel guarantees synchronization, so 89a34cb8450a
can be seen as a regression. This commit addresses the inter-context
synchronization case.

Cc: mesa-stable
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5731
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/5812
Fixes: 89a34cb8450a ("iris: switch to explicit busy tracking")
Tested-by: Konstantin Kharlamov <hi-angel@yandex.ru>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 src/gallium/drivers/iris/iris_batch.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/gallium/drivers/iris/iris_batch.c b/src/gallium/drivers/iris/iris_batch.c
index b7bde60aae7..1b0c5896d4f 100644
--- a/src/gallium/drivers/iris/iris_batch.c
+++ b/src/gallium/drivers/iris/iris_batch.c
@@ -835,6 +835,12 @@ update_bo_syncobjs(struct iris_batch *batch, struct iris_bo *bo, bool write)
       move_syncobj_to_batch(batch, &deps->write_syncobjs[other_batch_idx],
                             I915_EXEC_FENCE_WAIT);
 
+   /* If it's being written by our screen, wait on it too. This is relevant
+    * when there are multiple contexts on the same screen. */
+   if (deps->write_syncobjs[batch_idx])
+      move_syncobj_to_batch(batch, &deps->write_syncobjs[batch_idx],
+                            I915_EXEC_FENCE_WAIT);
+
    struct iris_syncobj *batch_syncobj = iris_batch_get_signal_syncobj(batch);
 
    if (write) {
@@ -847,6 +853,8 @@ update_bo_syncobjs(struct iris_batch *batch, struct iris_bo *bo, bool write)
 
       move_syncobj_to_batch(batch, &deps->read_syncobjs[other_batch_idx],
                            I915_EXEC_FENCE_WAIT);
+      move_syncobj_to_batch(batch, &deps->read_syncobjs[batch_idx],
+                           I915_EXEC_FENCE_WAIT);
 
    } else {
       /* If we're reading, replace the other read from our batch index. */
-- 
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