Merge branch 'master' of github.com:PX4/Firmware into fmuv2_bringup

src/drivers/ms5611/ms5611.cpp

@@ -791,7 +791,8 @@ start()
 	prom_u prom_buf;
 
 	if (g_dev != nullptr)
-		errx(1, "already started");
+		/* if already started, the still command succeeded */
+		errx(0, "already started");
 
 	device::Device *interface = nullptr;
 
@@ -1050,4 +1051,4 @@ ms5611_main(int argc, char *argv[])
 	}
 
 	errx(1, "unrecognised command, try 'start', 'test', 'reset' or 'info'");
-}
+}