radv: Implement alternate GFX9 scissor workaround.

This improves dota2 performance for me by 11% when I force the
GPU DPM level to low (otherwise dota2 is CPU limited for 4k on my
threadripper), which should be a large part of the radv-amdvlk gap.
(For me with that was radv 60.3 -> 66.6, while AMDVLK does about 68
fps)

It looks like dota2 rendered the GUI with a bunch of draws with
a SetScissors before almost each draw, causing a lot of pipeline
stalls.

I'm not really happy with the duplication of code, but overriding
radeon_set_context_reg would also be messy since we have the
pre-recorded pipelines and a bunch of si_cmd_buffer code, as well
as some memory->context reg loads for which things would be more
complicated.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
index 5ab577b..b6afa94 100644 (file)
--- a/src/amd/vulkan/radv_cmd_buffer.c
+++ b/src/amd/vulkan/radv_cmd_buffer.c
@@ -869,14 +869,6 @@ radv_emit_scissor(struct radv_cmd_buffer *cmd_buffer)
 {
        uint32_t count = cmd_buffer->state.dynamic.scissor.count;
 
-       /* Vega10/Raven scissor bug workaround. This must be done before VPORT
-        * scissor registers are changed. There is also a more efficient but
-        * more involved alternative workaround.
-        */
-       if (cmd_buffer->device->physical_device->has_scissor_bug) {
-               cmd_buffer->state.flush_bits |= RADV_CMD_FLAG_PS_PARTIAL_FLUSH;
-               si_emit_cache_flush(cmd_buffer);
-       }
        si_write_scissors(cmd_buffer->cs, 0, count,
                          cmd_buffer->state.dynamic.scissor.scissors,
                          cmd_buffer->state.dynamic.viewport.viewports,
@@ -1403,7 +1395,8 @@ radv_cmd_buffer_flush_dynamic_state(struct radv_cmd_buffer *cmd_buffer)
        if (states & (RADV_CMD_DIRTY_DYNAMIC_VIEWPORT))
                radv_emit_viewport(cmd_buffer);
 
-       if (states & (RADV_CMD_DIRTY_DYNAMIC_SCISSOR | RADV_CMD_DIRTY_DYNAMIC_VIEWPORT))
+       if (states & (RADV_CMD_DIRTY_DYNAMIC_SCISSOR | RADV_CMD_DIRTY_DYNAMIC_VIEWPORT) &&
+           !cmd_buffer->device->physical_device->has_scissor_bug)
                radv_emit_scissor(cmd_buffer);
 
        if (states & RADV_CMD_DIRTY_DYNAMIC_LINE_WIDTH)
@@ -2522,18 +2515,6 @@ void radv_CmdSetViewport(
        assert(firstViewport < MAX_VIEWPORTS);
        assert(total_count >= 1 && total_count <= MAX_VIEWPORTS);
 
-       if (cmd_buffer->device->physical_device->has_scissor_bug) {
-               /* Try to skip unnecessary PS partial flushes when the viewports
-                * don't change.
-                */
-               if (!(state->dirty & (RADV_CMD_DIRTY_DYNAMIC_VIEWPORT |
-                                     RADV_CMD_DIRTY_DYNAMIC_SCISSOR)) &&
-                   !memcmp(state->dynamic.viewport.viewports + firstViewport,
-                           pViewports, viewportCount * sizeof(*pViewports))) {
-                       return;
-               }
-       }
-
        memcpy(state->dynamic.viewport.viewports + firstViewport, pViewports,
               viewportCount * sizeof(*pViewports));
 
@@ -2553,18 +2534,6 @@ void radv_CmdSetScissor(
        assert(firstScissor < MAX_SCISSORS);
        assert(total_count >= 1 && total_count <= MAX_SCISSORS);
 
-       if (cmd_buffer->device->physical_device->has_scissor_bug) {
-               /* Try to skip unnecessary PS partial flushes when the scissors
-                * don't change.
-                */
-               if (!(state->dirty & (RADV_CMD_DIRTY_DYNAMIC_VIEWPORT |
-                                     RADV_CMD_DIRTY_DYNAMIC_SCISSOR)) &&
-                   !memcmp(state->dynamic.scissor.scissors + firstScissor,
-                           pScissors, scissorCount * sizeof(*pScissors))) {
-                       return;
-               }
-       }
-
        memcpy(state->dynamic.scissor.scissors + firstScissor, pScissors,
               scissorCount * sizeof(*pScissors));
 
@@ -3144,10 +3113,52 @@ radv_emit_draw_packets(struct radv_cmd_buffer *cmd_buffer,
        }
 }
 
+/*
+ * Vega and raven have a bug which triggers if there are multiple context
+ * register contexts active at the same time with different scissor values.
+ *
+ * There are two possible workarounds:
+ * 1) Wait for PS_PARTIAL_FLUSH every time the scissor is changed. That way
+ *    there is only ever 1 active set of scissor values at the same time.
+ *
+ * 2) Whenever the hardware switches contexts we have to set the scissor
+ *    registers again even if it is a noop. That way the new context gets
+ *    the correct scissor values.
+ *
+ * This implements option 2. radv_need_late_scissor_emission needs to
+ * return true on affected HW if radv_emit_all_graphics_states sets
+ * any context registers.
+ */
+static bool radv_need_late_scissor_emission(struct radv_cmd_buffer *cmd_buffer,
+                                            bool indexed_draw)
+{
+       struct radv_cmd_state *state = &cmd_buffer->state;
+
+       if (!cmd_buffer->device->physical_device->has_scissor_bug)
+               return false;
+
+       /* Assume all state changes except  these two can imply context rolls. */
+       if (cmd_buffer->state.dirty & ~(RADV_CMD_DIRTY_INDEX_BUFFER |
+                                       RADV_CMD_DIRTY_VERTEX_BUFFER |
+                                       RADV_CMD_DIRTY_PIPELINE))
+               return true;
+
+       if (cmd_buffer->state.emitted_pipeline != cmd_buffer->state.pipeline)
+               return true;
+
+       if (indexed_draw && state->pipeline->graphics.prim_restart_enable &&
+           (state->index_type ? 0xffffffffu : 0xffffu) != state->last_primitive_reset_index)
+               return true;
+
+       return false;
+}
+
 static void
 radv_emit_all_graphics_states(struct radv_cmd_buffer *cmd_buffer,
                              const struct radv_draw_info *info)
 {
+       bool late_scissor_emission = radv_need_late_scissor_emission(cmd_buffer, info->indexed);
+
        if ((cmd_buffer->state.dirty & RADV_CMD_DIRTY_FRAMEBUFFER) ||
            cmd_buffer->state.emitted_pipeline != cmd_buffer->state.pipeline)
                radv_emit_rbplus_state(cmd_buffer);
@@ -3177,6 +3188,9 @@ radv_emit_all_graphics_states(struct radv_cmd_buffer *cmd_buffer,
        radv_emit_draw_registers(cmd_buffer, info->indexed,
                                 info->instance_count > 1, info->indirect,
                                 info->indirect ? 0 : info->count);
+
+       if (late_scissor_emission)
+               radv_emit_scissor(cmd_buffer);
 }
 
 static void