diff --git a/hw/display/xlnx_dp.c b/hw/display/xlnx_dp.c
index 822355ecc6..43c7dd8e9c 100644
--- a/hw/display/xlnx_dp.c
+++ b/hw/display/xlnx_dp.c
@@ -380,13 +380,16 @@ static inline void xlnx_dp_audio_mix_buffer(XlnxDPState *s)
 static void xlnx_dp_audio_callback(void *opaque, int avail)
 {
     /*
-     * Get some data from the DPDMA and compute these data.
-     * Then wait for QEMU's audio subsystem to call this callback.
+     * Get the individual left and right audio streams from the DPDMA,
+     * and fill the output buffer with the combined stereo audio data
+     * adjusted by the volume controls.
+     * QEMU's audio subsystem will call this callback repeatedly;
+     * we return the data from the output buffer until it is emptied,
+     * and then we will read data from the DPDMA again.
      */
     XlnxDPState *s = XLNX_DP(opaque);
     size_t written = 0;
 
-    /* If there are already some data don't get more data. */
     if (s->byte_left == 0) {
         s->audio_data_available[0] = xlnx_dpdma_start_operation(s->dpdma, 4,
                                                                   true);