i965/gen6-7: Implement stall and flushes required prior to switching pipelines.

Switching the current pipeline while it's not completely idle or the
read and write caches aren't flushed can lead to corruption.  Fixes
misrendering of at least the following Khronos CTS test:

 ES31-CTS.shader_image_load_store.basic-allTargets-store-fs

The stall and flushes are no longer required on Gen8+.

v2: Emit PIPE_CONTROL with non-zero post-sync op before the write
    cache flush on SNB due to hardware bug. (Ken)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93323
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/brw_misc_state.c b/src/mesa/drivers/dri/i965/brw_misc_state.c
index 2b2f031..95edbc9 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_misc_state.c
+++ b/src/mesa/drivers/dri/i965/brw_misc_state.c
@@ -886,6 +886,43 @@ brw_emit_select_pipeline(struct brw_context *brw, enum brw_pipeline pipeline)
 
          brw->ctx.NewDriverState |= BRW_NEW_CC_STATE;
       }
+
+   } else if (brw->gen >= 6) {
+      /* From "BXML » GT » MI » vol1a GPU Overview » [Instruction]
+       * PIPELINE_SELECT [DevBWR+]":
+       *
+       *   Project: DEVSNB+
+       *
+       *   Software must ensure all the write caches are flushed through a
+       *   stalling PIPE_CONTROL command followed by another PIPE_CONTROL
+       *   command to invalidate read only caches prior to programming
+       *   MI_PIPELINE_SELECT command to change the Pipeline Select Mode.
+       */
+      const unsigned dc_flush =
+         brw->gen >= 7 ? PIPE_CONTROL_DATA_CACHE_INVALIDATE : 0;
+
+      if (brw->gen == 6) {
+         /* Hardware workaround: SNB B-Spec says:
+          *
+          *   Before a PIPE_CONTROL with Write Cache Flush Enable = 1, a
+          *   PIPE_CONTROL with any non-zero post-sync-op is required.
+          */
+         brw_emit_post_sync_nonzero_flush(brw);
+      }
+
+      brw_emit_pipe_control_flush(brw,
+                                  PIPE_CONTROL_RENDER_TARGET_FLUSH |
+                                  PIPE_CONTROL_DEPTH_CACHE_FLUSH |
+                                  dc_flush |
+                                  PIPE_CONTROL_NO_WRITE |
+                                  PIPE_CONTROL_CS_STALL);
+
+      brw_emit_pipe_control_flush(brw,
+                                  PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE |
+                                  PIPE_CONTROL_CONST_CACHE_INVALIDATE |
+                                  PIPE_CONTROL_STATE_CACHE_INVALIDATE |
+                                  PIPE_CONTROL_INSTRUCTION_INVALIDATE |
+                                  PIPE_CONTROL_NO_WRITE);
    }
 
    /* Select the pipeline */