RME RayDAT and AIO use a fixed buffer size of 16384 samples. With period
sizes of 32-4096, this translates to 4-512 periods.
The older RME cards have a variable buffer size but require exactly two
periods.
This patch enforces nperiods=2 on those cards.
Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Cc: <stable@vger.kernel.org> # 2.6.39+
Signed-off-by: Takashi Iwai <tiwai@suse.de>
                snd_pcm_hw_constraint_minmax(runtime,
                                             SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
                                             64, 8192);
+               snd_pcm_hw_constraint_minmax(runtime,
+                                            SNDRV_PCM_HW_PARAM_PERIODS,
+                                            2, 2);
                break;
        }
 
                snd_pcm_hw_constraint_minmax(runtime,
                                             SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
                                             64, 8192);
+               snd_pcm_hw_constraint_minmax(runtime,
+                                            SNDRV_PCM_HW_PARAM_PERIODS,
+                                            2, 2);
                break;
        }