From 1a3f041cd82bdd650fafd2456e3375d9aa421bc3 Mon Sep 17 00:00:00 2001
From: Rob Clark <robdclark@chromium.org>
Date: Mon, 22 Jul 2024 07:22:18 -0700
Subject: [PATCH] freedreno/a6xx: Implement reg stomper support

Useful to track down issues related to uninitialized regs.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30304>
---
 src/gallium/drivers/freedreno/a6xx/fd6_emit.cc  | 17 +++++++++++++++++
 .../drivers/freedreno/freedreno_screen.c        |  1 +
 src/gallium/drivers/freedreno/freedreno_util.h  |  1 +
 3 files changed, 19 insertions(+)

diff --git a/src/gallium/drivers/freedreno/a6xx/fd6_emit.cc b/src/gallium/drivers/freedreno/a6xx/fd6_emit.cc
index 5e3fb31a022..379d00f6aec 100644
--- a/src/gallium/drivers/freedreno/a6xx/fd6_emit.cc
+++ b/src/gallium/drivers/freedreno/a6xx/fd6_emit.cc
@@ -37,6 +37,7 @@
 #include "freedreno_query_hw.h"
 #include "freedreno_resource.h"
 #include "freedreno_state.h"
+#include "freedreno_stompable_regs.h"
 #include "freedreno_tracepoints.h"
 
 #include "fd6_blend.h"
@@ -802,6 +803,17 @@ fd6_emit_ccu_cntl(struct fd_ringbuffer *ring, struct fd_screen *screen, bool gme
 template void fd6_emit_cs_state<A6XX>(struct fd_context *ctx, struct fd_ringbuffer *ring, struct fd6_compute_state *cs);
 template void fd6_emit_cs_state<A7XX>(struct fd_context *ctx, struct fd_ringbuffer *ring, struct fd6_compute_state *cs);
 
+template <chip CHIP>
+static void
+fd6_emit_stomp(struct fd_ringbuffer *ring, const uint16_t *regs, size_t count)
+{
+   for (size_t i = 0; i < count; i++) {
+      if (fd_reg_stomp_allowed(CHIP, regs[i])) {
+         WRITE(regs[i], 0xffffffff);
+      }
+   }
+}
+
 /* emit setup at begin of new cmdstream buffer (don't rely on previous
  * state, there could have been a context switch between ioctls):
  */
@@ -815,6 +827,11 @@ fd6_emit_restore(struct fd_batch *batch, struct fd_ringbuffer *ring)
       trace_start_state_restore(&batch->trace, ring);
    }
 
+   if (FD_DBG(STOMP)) {
+      fd6_emit_stomp<CHIP>(ring, &RP_BLIT_REGS<CHIP>[0], ARRAY_SIZE(RP_BLIT_REGS<CHIP>));
+      fd6_emit_stomp<CHIP>(ring, &CMD_REGS<CHIP>[0], ARRAY_SIZE(CMD_REGS<CHIP>));
+   }
+
    OUT_PKT7(ring, CP_SET_MODE, 1);
    OUT_RING(ring, 0);
 
diff --git a/src/gallium/drivers/freedreno/freedreno_screen.c b/src/gallium/drivers/freedreno/freedreno_screen.c
index e102ee7b822..22638cd5569 100644
--- a/src/gallium/drivers/freedreno/freedreno_screen.c
+++ b/src/gallium/drivers/freedreno/freedreno_screen.c
@@ -98,6 +98,7 @@ static const struct debug_named_value fd_debug_options[] = {
    {"nofp16",    FD_DBG_NOFP16,   "Disable mediump precision lowering"},
    {"nohw",      FD_DBG_NOHW,     "Disable submitting commands to the HW"},
    {"nosbin",    FD_DBG_NOSBIN,   "Execute GMEM bins in raster order instead of 'S' pattern"},
+   {"stomp",     FD_DBG_STOMP,    "Enable register stomper"},
    DEBUG_NAMED_VALUE_END
 };
 /* clang-format on */
diff --git a/src/gallium/drivers/freedreno/freedreno_util.h b/src/gallium/drivers/freedreno/freedreno_util.h
index 0baba253043..2041be358a5 100644
--- a/src/gallium/drivers/freedreno/freedreno_util.h
+++ b/src/gallium/drivers/freedreno/freedreno_util.h
@@ -102,6 +102,7 @@ enum fd_debug_flag {
    FD_DBG_NOFP16       = BITFIELD_BIT(27),
    FD_DBG_NOHW         = BITFIELD_BIT(28),
    FD_DBG_NOSBIN       = BITFIELD_BIT(29),
+   FD_DBG_STOMP        = BITFIELD_BIT(30),
 };
 /* clang-format on */