Mesa (master): freedreno: Add a nohw flag to skip submitting to the kernel.

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Module: Mesa
Branch: master
Commit: fdcadf611e03f0dc8878fb032b62510c38fe069b
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=fdcadf611e03f0dc8878fb032b62510c38fe069b

Author: Eric Anholt <eric at anholt.net>
Date:   Mon May 11 13:53:48 2020 -0700

freedreno: Add a nohw flag to skip submitting to the kernel.

For some CPU-side-only optimizations, it can be nice to disable rendering
so that we can see what the impact is even on cases where the GPU can't
quite keep up.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4996>

---

 src/gallium/drivers/freedreno/freedreno_gmem.c   | 3 +++
 src/gallium/drivers/freedreno/freedreno_screen.c | 1 +
 src/gallium/drivers/freedreno/freedreno_util.h   | 1 +
 3 files changed, 5 insertions(+)

diff --git a/src/gallium/drivers/freedreno/freedreno_gmem.c b/src/gallium/drivers/freedreno/freedreno_gmem.c
index 78d2a3a7932..73db133ae4a 100644
--- a/src/gallium/drivers/freedreno/freedreno_gmem.c
+++ b/src/gallium/drivers/freedreno/freedreno_gmem.c
@@ -612,6 +612,9 @@ flush_ring(struct fd_batch *batch)
 	uint32_t timestamp;
 	int out_fence_fd = -1;
 
+	if (unlikely(fd_mesa_debug & FD_DBG_NOHW))
+		return;
+
 	fd_submit_flush(batch->submit, batch->in_fence_fd,
 			batch->needs_out_fence_fd ? &out_fence_fd : NULL,
 			&timestamp);
diff --git a/src/gallium/drivers/freedreno/freedreno_screen.c b/src/gallium/drivers/freedreno/freedreno_screen.c
index b44fee62bd7..fd15e1fe54b 100644
--- a/src/gallium/drivers/freedreno/freedreno_screen.c
+++ b/src/gallium/drivers/freedreno/freedreno_screen.c
@@ -90,6 +90,7 @@ static const struct debug_named_value debug_options[] = {
 		{"notile",    FD_DBG_NOTILE, "Disable tiling for all internal buffers"},
 		{"layout",    FD_DBG_LAYOUT, "Dump resource layouts"},
 		{"nofp16",    FD_DBG_NOFP16, "Disable mediump precision lowering"},
+		{"nohw",      FD_DBG_NOHW,   "Disable submitting commands to the HW"},
 		DEBUG_NAMED_VALUE_END
 };
 
diff --git a/src/gallium/drivers/freedreno/freedreno_util.h b/src/gallium/drivers/freedreno/freedreno_util.h
index 0557f0ffca2..c2380c86303 100644
--- a/src/gallium/drivers/freedreno/freedreno_util.h
+++ b/src/gallium/drivers/freedreno/freedreno_util.h
@@ -90,6 +90,7 @@ enum fd_debug_flag {
 	FD_DBG_NOTILE       = BITFIELD_BIT(25),
 	FD_DBG_LAYOUT       = BITFIELD_BIT(26),
 	FD_DBG_NOFP16       = BITFIELD_BIT(27),
+	FD_DBG_NOHW         = BITFIELD_BIT(28),
 };
 
 extern int fd_mesa_debug;