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- From e27e038a64e9a3499f76e9581ea67b4b81a33555 Mon Sep 17 00:00:00 2001
- From: Phil Elwell <phil@raspberrypi.org>
- Date: Thu, 21 Apr 2016 15:44:14 +0100
- Subject: [PATCH] bcm2835-i2s: Reduce the TX DREQ threshold
- TX FIFO overrun is thought to be the cause of channel swapping, so
- reducing the DREQ threshold seems reasonable and appears to be
- effective.
- See: https://github.com/raspberrypi/linux/issues/1417
- Signed-off-by: Phil Elwell <phil@raspberrypi.org>
- ---
- sound/soc/bcm/bcm2835-i2s.c | 21 ++++++++++++++-------
- 1 file changed, 14 insertions(+), 7 deletions(-)
- --- a/sound/soc/bcm/bcm2835-i2s.c
- +++ b/sound/soc/bcm/bcm2835-i2s.c
- @@ -555,15 +555,22 @@ static int bcm2835_i2s_hw_params(struct
-
- /* Setup the DMA parameters */
- regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_CS_A_REG,
- - BCM2835_I2S_RXTHR(1)
- - | BCM2835_I2S_TXTHR(1)
- - | BCM2835_I2S_DMAEN, 0xffffffff);
- + BCM2835_I2S_RXTHR(3)
- + | BCM2835_I2S_TXTHR(3)
- + | BCM2835_I2S_DMAEN,
- + BCM2835_I2S_RXTHR(1)
- + | BCM2835_I2S_TXTHR(1)
- + | BCM2835_I2S_DMAEN);
-
- regmap_update_bits(dev->i2s_regmap, BCM2835_I2S_DREQ_A_REG,
- - BCM2835_I2S_TX_PANIC(0x10)
- - | BCM2835_I2S_RX_PANIC(0x30)
- - | BCM2835_I2S_TX(0x30)
- - | BCM2835_I2S_RX(0x20), 0xffffffff);
- + BCM2835_I2S_TX_PANIC(0x7f)
- + | BCM2835_I2S_RX_PANIC(0x7f)
- + | BCM2835_I2S_TX(0x7f)
- + | BCM2835_I2S_RX(0x7f),
- + BCM2835_I2S_TX_PANIC(0x10)
- + | BCM2835_I2S_RX_PANIC(0x30)
- + | BCM2835_I2S_TX(0x20)
- + | BCM2835_I2S_RX(0x20));
-
- /* Clear FIFOs */
- bcm2835_i2s_clear_fifos(dev, true, true);
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