[Mesa-dev] [PATCH 1/3] panfrost: Make sure a clear does not re-use a pre-existing batch

[Boris Brezillon]

glClear()s are expected to be the first thing GL apps do before drawing
new things. If there's already an existing batch targetting the same
FBO that has draws attached to it, we should make sure the new clear
gets a new batch assigned to guaranteed that the FB content is actually
cleared with the requested color/depth/stencil values.

We create a panfrost_get_fresh_batch_for_fbo() helper for that and
call it from panfrost_clear().

Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
---
 src/gallium/drivers/panfrost/pan_context.c |  2 +-
 src/gallium/drivers/panfrost/pan_job.c     | 21 +++++++++++++++++++++
 src/gallium/drivers/panfrost/pan_job.h     |  3 +++
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/panfrost/pan_context.c b/src/gallium/drivers/panfrost/pan_context.c
index ac01461a07fe..b2f2a9da7a51 100644
--- a/src/gallium/drivers/panfrost/pan_context.c
+++ b/src/gallium/drivers/panfrost/pan_context.c
@@ -162,7 +162,7 @@ panfrost_clear(
         double depth, unsigned stencil)
 {
         struct panfrost_context *ctx = pan_context(pipe);
-        struct panfrost_batch *batch = panfrost_get_batch_for_fbo(ctx);
+        struct panfrost_batch *batch = panfrost_get_fresh_batch_for_fbo(ctx);
 
         panfrost_batch_add_fbo_bos(batch);
         panfrost_batch_clear(batch, buffers, color, depth, stencil);
diff --git a/src/gallium/drivers/panfrost/pan_job.c b/src/gallium/drivers/panfrost/pan_job.c
index d8330bc133a6..4ec2aa0565d7 100644
--- a/src/gallium/drivers/panfrost/pan_job.c
+++ b/src/gallium/drivers/panfrost/pan_job.c
@@ -298,6 +298,27 @@ panfrost_get_batch_for_fbo(struct panfrost_context *ctx)
         return batch;
 }
 
+struct panfrost_batch *
+panfrost_get_fresh_batch_for_fbo(struct panfrost_context *ctx)
+{
+        struct panfrost_batch *batch;
+
+        batch = panfrost_get_batch(ctx, &ctx->pipe_framebuffer);
+
+        /* The batch has no draw/clear queued, let's return it directly.
+         * Note that it's perfectly fine to re-use a batch with an
+         * existing clear, we'll just update it with the new clear request.
+         */
+        if (!batch->last_job.gpu)
+                return batch;
+
+        /* Otherwise, we need to freeze the existing one and instantiate a new
+         * one.
+         */
+        panfrost_freeze_batch(batch);
+        return panfrost_get_batch(ctx, &ctx->pipe_framebuffer);
+}
+
 static bool
 panfrost_batch_fence_is_signaled(struct panfrost_batch_fence *fence)
 {
diff --git a/src/gallium/drivers/panfrost/pan_job.h b/src/gallium/drivers/panfrost/pan_job.h
index e1b1f56a2e64..0bd78bba267a 100644
--- a/src/gallium/drivers/panfrost/pan_job.h
+++ b/src/gallium/drivers/panfrost/pan_job.h
@@ -172,6 +172,9 @@ panfrost_batch_fence_reference(struct panfrost_batch_fence *batch);
 struct panfrost_batch *
 panfrost_get_batch_for_fbo(struct panfrost_context *ctx);
 
+struct panfrost_batch *
+panfrost_get_fresh_batch_for_fbo(struct panfrost_context *ctx);
+
 void
 panfrost_batch_init(struct panfrost_context *ctx);
 
-- 
2.21.0