switch (cmd) {
        case EM28XX_CAPTURE_STREAM_EN:
-               if (dev->adev.capture_stream == STREAM_OFF && arg == 1) {
+               if (dev->adev.capture_stream == STREAM_OFF && arg == EM28XX_START_AUDIO) {
                        dev->adev.capture_stream = STREAM_ON;
                        em28xx_init_audio_isoc(dev);
-               } else if (dev->adev.capture_stream == STREAM_ON && arg == 0) {
+               } else if (dev->adev.capture_stream == STREAM_ON && arg == EM28XX_STOP_AUDIO) {
                        dev->adev.capture_stream = STREAM_OFF;
                        em28xx_deinit_isoc_audio(dev);
                } else {
        dprintk("Stop capture, if needed\n");
 
        if (dev->adev.capture_stream == STREAM_ON)
-               em28xx_cmd(dev, EM28XX_CAPTURE_STREAM_EN, 0);
+               em28xx_cmd(dev, EM28XX_CAPTURE_STREAM_EN, EM28XX_STOP_AUDIO);
 
        return 0;
 }
        spin_lock(&dev->adev.slock);
        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
-               em28xx_cmd(dev, EM28XX_CAPTURE_STREAM_EN, 1);
+               em28xx_cmd(dev, EM28XX_CAPTURE_STREAM_EN, EM28XX_START_AUDIO);
                retval = 0;
                break;
        case SNDRV_PCM_TRIGGER_STOP:
-               em28xx_cmd(dev, EM28XX_CAPTURE_STREAM_EN, 0);
+               em28xx_cmd(dev, EM28XX_CAPTURE_STREAM_EN, EM28XX_STOP_AUDIO);
                retval = 0;
                break;
        default:
 
 #define EM28XX_BOARD_NOT_VALIDATED 1
 #define EM28XX_BOARD_VALIDATED    0
 
+/* Params for em28xx_cmd() audio */
+#define EM28XX_START_AUDIO      1
+#define EM28XX_STOP_AUDIO       0
+
 /* maximum number of em28xx boards */
 #define EM28XX_MAXBOARDS 4 /*FIXME: should be bigger */