The default value of the PERIOD_LEN register is 0 and results in axi-i2s keeping TLAST always asserted in its AXI Stream output.
When the AXI Stream is sent to a Xilinx AXI-DMA, this results in the DMA generating an interrupt flood and ALSA produce a corrupted recording. This is because AXI-DMA raises an interrupt whenever TLAST is active.
Fix by setting the PERIOD_LEN register as soon as the period is known. This way TLAST is emitted once per period, and the DMA raises interrupts correctly.
Signed-off-by: Luca Ceresoli luca@lucaceresoli.net --- sound/soc/adi/axi-i2s.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/sound/soc/adi/axi-i2s.c b/sound/soc/adi/axi-i2s.c index 4c23381727a1..af581a313a40 100644 --- a/sound/soc/adi/axi-i2s.c +++ b/sound/soc/adi/axi-i2s.c @@ -24,6 +24,7 @@ #define AXI_I2S_REG_CTRL 0x04 #define AXI_I2S_REG_CLK_CTRL 0x08 #define AXI_I2S_REG_STATUS 0x10 +#define AXI_I2S_REG_PERIOD_LEN 0x18
#define AXI_I2S_REG_RX_FIFO 0x28 #define AXI_I2S_REG_TX_FIFO 0x2C @@ -101,6 +102,17 @@ static int axi_i2s_hw_params(struct snd_pcm_substream *substream, return 0; }
+static int axi_i2s_prepare(struct snd_pcm_substream *substream, + struct snd_soc_dai *dai) +{ + struct axi_i2s *i2s = snd_soc_dai_get_drvdata(dai); + unsigned int period_bytes = snd_pcm_lib_period_bytes(substream); + + /* adi_i2s counts 32-bit words, thus divide bytes by 4 */ + return regmap_write(i2s->regmap, AXI_I2S_REG_PERIOD_LEN, + (period_bytes / 4) - 1); +} + static int axi_i2s_startup(struct snd_pcm_substream *substream, struct snd_soc_dai *dai) { @@ -147,6 +159,7 @@ static const struct snd_soc_dai_ops axi_i2s_dai_ops = { .shutdown = axi_i2s_shutdown, .trigger = axi_i2s_trigger, .hw_params = axi_i2s_hw_params, + .prepare = axi_i2s_prepare, };
static struct snd_soc_dai_driver axi_i2s_dai = { @@ -175,7 +188,7 @@ static const struct regmap_config axi_i2s_regmap_config = { .reg_bits = 32, .reg_stride = 4, .val_bits = 32, - .max_register = AXI_I2S_REG_STATUS, + .max_register = AXI_I2S_REG_PERIOD_LEN, };
static int axi_i2s_probe(struct platform_device *pdev)