.mask = 0
 };
 
+static void
+rme96_set_buffer_size_constraint(struct rme96 *rme96,
+                                struct snd_pcm_runtime *runtime)
+{
+       unsigned int size;
+
+       snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES,
+                                    RME96_BUFFER_SIZE, RME96_BUFFER_SIZE);
+       if ((size = rme96->playback_periodsize) != 0 ||
+           (size = rme96->capture_periodsize) != 0)
+               snd_pcm_hw_constraint_minmax(runtime,
+                                            SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
+                                            size, size);
+       else
+               snd_pcm_hw_constraint_list(runtime, 0,
+                                          SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
+                                          &hw_constraints_period_bytes);
+}
+
 static int
 snd_rme96_playback_spdif_open(struct snd_pcm_substream *substream)
 {
                 runtime->hw.rate_min = rate;
                 runtime->hw.rate_max = rate;
        }        
-       snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, RME96_BUFFER_SIZE, RME96_BUFFER_SIZE);
-       snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, &hw_constraints_period_bytes);
+       rme96_set_buffer_size_constraint(rme96, runtime);
 
        rme96->wcreg_spdif_stream = rme96->wcreg_spdif;
        rme96->spdif_ctl->vd[0].access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
        rme96->capture_substream = substream;
        spin_unlock_irq(&rme96->lock);
        
-       snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, RME96_BUFFER_SIZE, RME96_BUFFER_SIZE);
-       snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, &hw_constraints_period_bytes);
-
+       rme96_set_buffer_size_constraint(rme96, runtime);
        return 0;
 }
 
                 runtime->hw.rate_min = rate;
                 runtime->hw.rate_max = rate;
        }        
-       snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, RME96_BUFFER_SIZE, RME96_BUFFER_SIZE);
-       snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, &hw_constraints_period_bytes);
+       rme96_set_buffer_size_constraint(rme96, runtime);
        return 0;
 }
 
        rme96->capture_substream = substream;
        spin_unlock_irq(&rme96->lock);
 
-       snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, RME96_BUFFER_SIZE, RME96_BUFFER_SIZE);
-       snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, &hw_constraints_period_bytes);
+       rme96_set_buffer_size_constraint(rme96, runtime);
        return 0;
 }