Revert "drm/i915/tgl: Add extra hdc flush workaround"

This reverts commit 36a6b5d9.

The commit takes care Wa_1604544889 which was fixed on a0 stepping based on
a0 replan. So no SW workaround is required on any stepping now.
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Caz Yokoyama <caz.yokoyama@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Fixes: 36a6b5d9 ("drm/i915/tgl: Add extra hdc flush workaround")
Link: https://patchwork.freedesktop.org/patch/msgid/1c751032ce79c80c5485cae315f1a9904ce07cac.1583359940.git.caz.yokoyama@intel.com

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -4165,26 +4165,6 @@ static int gen12_emit_flush_render(struct i915_request *request,
 
 		*cs++ = preparser_disable(false);
 		intel_ring_advance(request, cs);
-
-		/*
-		 * Wa_1604544889:tgl
-		 */
-		if (IS_TGL_REVID(request->i915, TGL_REVID_A0, TGL_REVID_A0)) {
-			flags = 0;
-			flags |= PIPE_CONTROL_CS_STALL;
-			flags |= PIPE_CONTROL_HDC_PIPELINE_FLUSH;
-
-			flags |= PIPE_CONTROL_STORE_DATA_INDEX;
-			flags |= PIPE_CONTROL_QW_WRITE;
-
-			cs = intel_ring_begin(request, 6);
-			if (IS_ERR(cs))
-				return PTR_ERR(cs);
-
-			cs = gen8_emit_pipe_control(cs, flags,
-						    LRC_PPHWSP_SCRATCH_ADDR);
-			intel_ring_advance(request, cs);
-		}
 	}
 
 	return 0;