sound: oxygen: reset DMA when stream is closed

When a PCM stream is closed, flush the corresponding DMA channel.
Otherwise, the DMA controller would continue to output the last sample
which would result in a DC offset on the output.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/oxygen/oxygen_pcm.c b/sound/pci/oxygen/oxygen_pcm.c
index c262049961e15a0dd9840645f753584373dac52a..3b5ca70c9d4d2745223ac6f66102f8fd78e11161 100644 (file)
--- a/sound/pci/oxygen/oxygen_pcm.c
+++ b/sound/pci/oxygen/oxygen_pcm.c
@@ -487,10 +487,14 @@ static int oxygen_hw_free(struct snd_pcm_substream *substream)
 {
        struct oxygen *chip = snd_pcm_substream_chip(substream);
        unsigned int channel = oxygen_substream_channel(substream);
+       unsigned int channel_mask = 1 << channel;
 
        spin_lock_irq(&chip->reg_lock);
-       chip->interrupt_mask &= ~(1 << channel);
+       chip->interrupt_mask &= ~channel_mask;
        oxygen_write16(chip, OXYGEN_INTERRUPT_MASK, chip->interrupt_mask);
+
+       oxygen_set_bits8(chip, OXYGEN_DMA_FLUSH, channel_mask);
+       oxygen_clear_bits8(chip, OXYGEN_DMA_FLUSH, channel_mask);
        spin_unlock_irq(&chip->reg_lock);
 
        return snd_pcm_lib_free_pages(substream);