ALSA: pcmtest: Move buffer iterator initialization to prepare callback

Trigger callback is not the best place for buffer iterator
initialization, so move it out to the prepare callback, where it
have to be.

Minor enhancement: remove blank line.
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230804110740.9867-1-ivan.orlov0322@gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/pcmtest.c

@@ -92,7 +92,6 @@ MODULE_PARM_DESC(inject_trigger_err, "Inject EINVAL error in the 'trigger' callb
 module_param(inject_open_err, bool, 0600);
 MODULE_PARM_DESC(inject_open_err, "Inject EBUSY error in the 'open' callback");
 
-
 struct pcmtst {
 	struct snd_pcm *pcm;
 	struct snd_card *card;
@@ -405,25 +404,9 @@ static int snd_pcmtst_pcm_close(struct snd_pcm_substream *substream)
 
 static int snd_pcmtst_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 {
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct pcmtst_buf_iter *v_iter = runtime->private_data;
-
 	if (inject_trigger_err)
 		return -EINVAL;
 
-	v_iter->sample_bytes = runtime->sample_bits / 8;
-	v_iter->period_bytes = frames_to_bytes(runtime, runtime->period_size);
-	if (runtime->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED ||
-	    runtime->access == SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED) {
-		v_iter->chan_block = runtime->dma_bytes / runtime->channels;
-		v_iter->interleaved = false;
-	} else {
-		v_iter->interleaved = true;
-	}
-	// We want to record RATE * ch_cnt samples per sec, it is rate * sample_bytes * ch_cnt bytes
-	v_iter->s_rw_ch = runtime->rate / TIMER_PER_SEC;
-	v_iter->b_rw = v_iter->s_rw_ch * v_iter->sample_bytes * runtime->channels;
-
 	return 0;
 }
 
@@ -454,8 +437,24 @@ static void pcmtst_pdev_release(struct device *dev)
 
 static int snd_pcmtst_pcm_prepare(struct snd_pcm_substream *substream)
 {
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct pcmtst_buf_iter *v_iter = runtime->private_data;
+
 	if (inject_prepare_err)
 		return -EINVAL;
+
+	v_iter->sample_bytes = samples_to_bytes(runtime, 1);
+	v_iter->period_bytes = snd_pcm_lib_period_bytes(substream);
+	v_iter->interleaved = true;
+	if (runtime->access == SNDRV_PCM_ACCESS_RW_NONINTERLEAVED ||
+	    runtime->access == SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED) {
+		v_iter->chan_block = snd_pcm_lib_buffer_bytes(substream) / runtime->channels;
+		v_iter->interleaved = false;
+	}
+	// We want to record RATE * ch_cnt samples per sec, it is rate * sample_bytes * ch_cnt bytes
+	v_iter->s_rw_ch = runtime->rate / TIMER_PER_SEC;
+	v_iter->b_rw = v_iter->s_rw_ch * v_iter->sample_bytes * runtime->channels;
+
 	return 0;
 }