rsx: Loosen the access ordering guarantees a bit

Author: kd-11

rpcs3/Emu/RSX/Common/texture_cache.h

@@ -3740,9 +3740,12 @@ namespace rsx
 					}
 				}
 
-				// MM flush before commit below
-				const auto mm_flush_range = utils::address_range64::start_length(reinterpret_cast<u64>(dst.pixels), dst_payload_length);
-				rsx::mm_flush({ mm_flush_range });
+				// MM flush before commit below. For performance reasons, only flush when writing to CELL memory.
+				if (rsx::classify_location(dst.rsx_address) == CELL_GCM_LOCATION_MAIN)
+				{
+					const auto mm_flush_range = utils::address_range64::start_length(reinterpret_cast<u64>(dst.pixels), dst_payload_length);
+					rsx::mm_flush({ mm_flush_range });
+				}
 
 				// Commit any pending writes before we do the transfer. Writes will be done on super_ptr so locking beforehand is ok.
 				m_rtts.prepare_transfer_target(cmd, dst_subres.surface, rsx::surface_access::transfer_write, std::forward<Args>(extras)...);