[PATCH 1/2] ALSA: sb: Don't allow changing the DMA mode during operations

[PATCH 1/2] ALSA: sb: Don't allow changing the DMA mode during operations

[Takashi Iwai]

When a PCM stream is already running, one shouldn't change the DMA
mode via kcontrol, which may screw up the hardware.  Return -EBUSY
instead.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=218185
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/isa/sb/sb16_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/isa/sb/sb16_main.c b/sound/isa/sb/sb16_main.c
index 74db11525003..c4930efd44e3 100644
--- a/sound/isa/sb/sb16_main.c
+++ b/sound/isa/sb/sb16_main.c
@@ -703,6 +703,9 @@ static int snd_sb16_dma_control_put(struct snd_kcontrol *kcontrol, struct snd_ct
 	unsigned char nval, oval;
 	int change;
 	
+	if (chip->mode & (SB_MODE_PLAYBACK | SB_MODE_CAPTURE))
+		return -EBUSY;
+
 	nval = ucontrol->value.enumerated.item[0];
 	if (nval > 2)
 		return -EINVAL;
-- 
2.49.0

[PATCH 2/2] ALSA: sb: Force to disable DMAs once when DMA mode is changed

[Takashi Iwai]

When the DMA mode is changed on the (still real!) SB AWE32 after
playing a stream and closing, the previous DMA setup was still
silently kept, and it can confuse the hardware, resulting in the
unexpected noises.  As a workaround, enforce the disablement of DMA
setups when the DMA setup is changed by the kcontrol.

https://bugzilla.kernel.org/show_bug.cgi?id=218185
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/isa/sb/sb16_main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/isa/sb/sb16_main.c b/sound/isa/sb/sb16_main.c
index c4930efd44e3..5a083eecaa6b 100644
--- a/sound/isa/sb/sb16_main.c
+++ b/sound/isa/sb/sb16_main.c
@@ -714,6 +714,10 @@ static int snd_sb16_dma_control_put(struct snd_kcontrol *kcontrol, struct snd_ct
 	change = nval != oval;
 	snd_sb16_set_dma_mode(chip, nval);
 	spin_unlock_irqrestore(&chip->reg_lock, flags);
+	if (change) {
+		snd_dma_disable(chip->dma8);
+		snd_dma_disable(chip->dma16);
+	}
 	return change;
 }
 
-- 
2.49.0