ASoC: dwc: Fix full-duplex mode

Configuration of the DMA register was carelessly zeroing bits that may
used by a stream in the other direction. Preserve them instead.

See: https://github.com/raspberrypi/linux/issues/5741

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

diff --git a/sound/soc/dwc/dwc-i2s.c b/sound/soc/dwc/dwc-i2s.c
index c196ad7..11cd83b 100644 (file)
--- a/sound/soc/dwc/dwc-i2s.c
+++ b/sound/soc/dwc/dwc-i2s.c
@@ -235,10 +235,17 @@ static void dw_i2s_config(struct dw_i2s_dev *dev, int stream)
 {
        u32 ch_reg;
        struct i2s_clk_config_data *config = &dev->config;
-       u32 dmacr = 0;
+       u32 dmacr;
 
        i2s_disable_channels(dev, stream);
 
+       dmacr = i2s_read_reg(dev->i2s_base, I2S_DMACR);
+
+       if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+               dmacr &= ~(DMACR_DMAEN_TXCH0 * 0xf);
+       else
+               dmacr &= ~(DMACR_DMAEN_RXCH0 * 0xf);
+
        for (ch_reg = 0; ch_reg < (config->chan_nr / 2); ch_reg++) {
                if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
                        i2s_write_reg(dev->i2s_base, TCR(ch_reg),
@@ -258,10 +265,6 @@ static void dw_i2s_config(struct dw_i2s_dev *dev, int stream)
                        dmacr |= (DMACR_DMAEN_RXCH0 << ch_reg);
                }
        }
-       if (stream == SNDRV_PCM_STREAM_PLAYBACK)
-               dmacr |= DMACR_DMAEN_TX;
-       else if (stream == SNDRV_PCM_STREAM_CAPTURE)
-               dmacr |= DMACR_DMAEN_RX;
 
        i2s_write_reg(dev->i2s_base, I2S_DMACR, dmacr);
 }
@@ -370,10 +373,13 @@ static int dw_i2s_startup(struct snd_pcm_substream *substream,
 
        dw_i2s_config(dev, substream->stream);
        dmacr = i2s_read_reg(dev->i2s_base, I2S_DMACR);
-       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
                dma_data = &dev->play_dma_data;
-       else if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+               dmacr |= DMACR_DMAEN_TX;
+       } else if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
                dma_data = &dev->capture_dma_data;
+               dmacr |= DMACR_DMAEN_RX;
+       }
 
        snd_soc_dai_set_dma_data(cpu_dai, substream, (void *)dma_data);
        i2s_write_reg(dev->i2s_base, I2S_DMACR, dmacr);