Mesa (master): radeonsi: don't wait for idle at the end of gfx IBs

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Module: Mesa
Branch: master
Commit: 470b319813b0880ac106cfd70255d96421b9bec6
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=470b319813b0880ac106cfd70255d96421b9bec6

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Mon May  4 17:41:41 2020 -0400

radeonsi: don't wait for idle at the end of gfx IBs

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5506>

---

 src/gallium/drivers/radeonsi/si_gfx_cs.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/gallium/drivers/radeonsi/si_gfx_cs.c b/src/gallium/drivers/radeonsi/si_gfx_cs.c
index 64b216bf880..5581c46ebbd 100644
--- a/src/gallium/drivers/radeonsi/si_gfx_cs.c
+++ b/src/gallium/drivers/radeonsi/si_gfx_cs.c
@@ -72,12 +72,26 @@ void si_flush_gfx_cs(struct si_context *ctx, unsigned flags, struct pipe_fence_h
 {
    struct radeon_cmdbuf *cs = ctx->gfx_cs;
    struct radeon_winsys *ws = ctx->ws;
+   struct si_screen *sscreen = ctx->screen;
    const unsigned wait_ps_cs = SI_CONTEXT_PS_PARTIAL_FLUSH | SI_CONTEXT_CS_PARTIAL_FLUSH;
    unsigned wait_flags = 0;
 
    if (ctx->gfx_flush_in_progress)
       return;
 
+   /* The amdgpu kernel driver synchronizes execution for shared DMABUFs between
+    * processes on DRM >= 3.39.0, so we don't have to wait at the end of IBs to
+    * make sure everything is idle.
+    *
+    * The amdgpu winsys synchronizes execution for buffers shared by different
+    * contexts within the same process.
+    *
+    * Interop with AMDVLK, RADV, or OpenCL within the same process requires
+    * explicit fences or glFinish.
+    */
+   if (sscreen->info.is_amdgpu && sscreen->info.drm_minor >= 39)
+      flags |= RADEON_FLUSH_START_NEXT_GFX_IB_NOW;
+
    if (!ctx->screen->info.kernel_flushes_tc_l2_after_ib) {
       wait_flags |= wait_ps_cs | SI_CONTEXT_INV_L2;
    } else if (ctx->chip_class == GFX6) {