From: Esben Haabendal <eha@xxxxxxxx>
This fixes a race condition, where the DMAEN bit ends up being set after
I2C slave has transmitted a byte following the dummy read. When that
happens, an interrupt is generated instead, and no DMA request is generated
to kickstart the DMA read, and a timeout happens after DMA_TIMEOUT (1 sec).
Fixed by setting the DMAEN bit before the dummy read.
Signed-off-by: Esben Haabendal <eha@xxxxxxxx>
---
drivers/i2c/busses/i2c-imx.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 39cfd98c7b23..d86f152176a4 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -668,9 +668,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
struct imx_i2c_dma *dma = i2c_imx->dma;
struct device *dev = &i2c_imx->adapter.dev;
- temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
- temp |= I2CR_DMAEN;
- imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
dma->chan_using = dma->chan_rx;
dma->dma_transfer_dir = DMA_DEV_TO_MEM;
@@ -810,6 +807,11 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
if ((msgs->len - 1) || block_data)
temp &= ~I2CR_TXAK;
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+ if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data) {
+ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+ temp |= I2CR_DMAEN;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+ }
imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */
dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);
--
2.18.0
