ALSA: emu10k1: skip pointless cache setup for extra voices

Given that the data is going to be ignored anyway, and that the cache
does not influence interrupt timing (which is the purpose of the extra
voices), it's pointless to pre-fill the cache.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230517174256.3657060-4-oswald.buddenhagen@gmx.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/emu10k1/emupcm.c

@@ -528,14 +528,15 @@ static int snd_emu10k1_capture_prepare(struct snd_pcm_substream *substream)
 	return 0;
 }
 
-static void snd_emu10k1_playback_invalidate_cache(struct snd_emu10k1 *emu, int extra, struct snd_emu10k1_voice *evoice)
+static void snd_emu10k1_playback_invalidate_cache(struct snd_emu10k1 *emu,
+						  struct snd_emu10k1_voice *evoice)
 {
 	struct snd_pcm_runtime *runtime;
 	unsigned int voice, stereo, i, ccis, cra = 64, cs, sample;
 
 	runtime = evoice->epcm->substream->runtime;
 	voice = evoice->number;
-	stereo = (!extra && runtime->channels == 2);
+	stereo = (runtime->channels == 2);
 	sample = snd_pcm_format_width(runtime->format) == 16 ? 0 : 0x80808080;
 	ccis = emu10k1_ccis(stereo, sample == 0);
 	/* set cs to 2 * number of cache registers beside the invalidated */
@@ -658,8 +659,7 @@ static int snd_emu10k1_playback_trigger(struct snd_pcm_substream *substream,
 	spin_lock(&emu->reg_lock);
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
-		snd_emu10k1_playback_invalidate_cache(emu, 1, epcm->extra);	/* do we need this? */
-		snd_emu10k1_playback_invalidate_cache(emu, 0, epcm->voices[0]);
+		snd_emu10k1_playback_invalidate_cache(emu, epcm->voices[0]);
 		fallthrough;
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 	case SNDRV_PCM_TRIGGER_RESUME:
@@ -803,9 +803,8 @@ static int snd_emu10k1_efx_playback_trigger(struct snd_pcm_substream *substream,
 	case SNDRV_PCM_TRIGGER_START:
 		/* prepare voices */
 		for (i = 0; i < NUM_EFX_PLAYBACK; i++) {	
-			snd_emu10k1_playback_invalidate_cache(emu, 0, epcm->voices[i]);
+			snd_emu10k1_playback_invalidate_cache(emu, epcm->voices[i]);
 		}
-		snd_emu10k1_playback_invalidate_cache(emu, 1, epcm->extra);
 		fallthrough;
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 	case SNDRV_PCM_TRIGGER_RESUME: