diff --git a/sound/isa/sb/sb16_csp.c b/sound/isa/sb/sb16_csp.c
index ef1289cc78a4..30021ab5e0e9 100644
--- a/sound/isa/sb/sb16_csp.c
+++ b/sound/isa/sb/sb16_csp.c
@@ -814,6 +814,7 @@ static int snd_sb_csp_start(struct snd_sb_csp * p, int sample_width, int channel
 	mixR = snd_sbmixer_read(p->chip, SB_DSP4_PCM_DEV + 1);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL & 0x7);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR & 0x7);
+	spin_unlock_irqrestore(&p->chip->mixer_lock, flags);
 
 	spin_lock(&p->chip->reg_lock);
 	set_mode_register(p->chip, 0xc0);	/* c0 = STOP */
@@ -853,6 +854,7 @@ static int snd_sb_csp_start(struct snd_sb_csp * p, int sample_width, int channel
 	spin_unlock(&p->chip->reg_lock);
 
 	/* restore PCM volume */
+	spin_lock_irqsave(&p->chip->mixer_lock, flags);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR);
 	spin_unlock_irqrestore(&p->chip->mixer_lock, flags);
@@ -878,6 +880,7 @@ static int snd_sb_csp_stop(struct snd_sb_csp * p)
 	mixR = snd_sbmixer_read(p->chip, SB_DSP4_PCM_DEV + 1);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL & 0x7);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR & 0x7);
+	spin_unlock_irqrestore(&p->chip->mixer_lock, flags);
 
 	spin_lock(&p->chip->reg_lock);
 	if (p->running & SNDRV_SB_CSP_ST_QSOUND) {
@@ -892,6 +895,7 @@ static int snd_sb_csp_stop(struct snd_sb_csp * p)
 	spin_unlock(&p->chip->reg_lock);
 
 	/* restore PCM volume */
+	spin_lock_irqsave(&p->chip->mixer_lock, flags);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL);
 	snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR);
 	spin_unlock_irqrestore(&p->chip->mixer_lock, flags);