ALSA - au88x0 - Add buffer bytes constraints

This allow application such as gstreamer and wine which use
snd_pcm_hw_params_set_buffer_time_near() won't fail any more
since sound chips require special containt power 2 period bytes
Signed-off-by: Raymond Yau <superquad.vortex2@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/au88x0/au88x0_pcm.c

@@ -44,10 +44,10 @@ static struct snd_pcm_hardware snd_vortex_playback_hw_adb = {
 	.channels_min = 1,
 	.channels_max = 2,
 	.buffer_bytes_max = 0x10000,
-	.period_bytes_min = 0x1,
+	.period_bytes_min = 0x20,
 	.period_bytes_max = 0x1000,
 	.periods_min = 2,
-	.periods_max = 32,
+	.periods_max = 1024,
 };
 
 #ifndef CHIP_AU8820
@@ -140,6 +140,9 @@ static int snd_vortex_pcm_open(struct snd_pcm_substream *substream)
 					SNDRV_PCM_HW_PARAM_PERIOD_BYTES)) < 0)
 		return err;
 
+	snd_pcm_hw_constraint_step(runtime, 0,
+					SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 64);
+
 	if (VORTEX_PCM_TYPE(substream->pcm) != VORTEX_PCM_WT) {
 #ifndef CHIP_AU8820
 		if (VORTEX_PCM_TYPE(substream->pcm) == VORTEX_PCM_A3D) {