diff options
| author | Esben Haabendal <eha@deif.com> | 2018-08-16 10:43:12 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-08-20 11:13:09 +0200 |
| commit | bed4ff1ed4d8f2ef5007c5c6ae1b29c5677a3632 (patch) | |
| tree | 62e0e8b251ca36d6eadee3df8013e36962b23a37 /drivers/i2c/busses/i2c-imx.c | |
| parent | 5c18d12ced225fa0ad5a03fb42bbb293815d1342 (diff) | |
| download | lwn-bed4ff1ed4d8f2ef5007c5c6ae1b29c5677a3632.tar.gz lwn-bed4ff1ed4d8f2ef5007c5c6ae1b29c5677a3632.zip | |
i2c: imx: Fix race condition in dma read
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@deif.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
Diffstat (limited to 'drivers/i2c/busses/i2c-imx.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-imx.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 0207e194f84b..eb11ac3d6aba 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; @@ -784,6 +781,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo int i, result; unsigned int temp; int block_data = msgs->flags & I2C_M_RECV_LEN; + int use_dma = i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data; dev_dbg(&i2c_imx->adapter.dev, "<%s> write slave address: addr=0x%x\n", @@ -810,12 +808,14 @@ 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; + if (use_dma) + 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__); - if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data) + if (use_dma) return i2c_imx_dma_read(i2c_imx, msgs, is_lastmsg); /* read data */ |