From bed4ff1ed4d8f2ef5007c5c6ae1b29c5677a3632 Mon Sep 17 00:00:00 2001 From: Esben Haabendal Date: Thu, 16 Aug 2018 10:43:12 +0200 Subject: i2c: imx: Fix race condition in dma read MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Acked-by: Uwe Kleine-König Signed-off-by: Wolfram Sang Cc: stable@kernel.org --- drivers/i2c/busses/i2c-imx.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/i2c/busses/i2c-imx.c') 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 */ -- cgit v1.2.3 From ef456a2de3716e2a38382ff2aa9a9c52962e7e84 Mon Sep 17 00:00:00 2001 From: Esben Haabendal Date: Thu, 16 Aug 2018 10:43:13 +0200 Subject: i2c: imx: Simplify stopped state tracking MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Always update the stopped state when busy status have been checked. This is identical to what was done before, with the exception of error handling. Without this change, some errors cause the stopped state to be left in incorrect state in i2c_imx_stop(), i2c_imx_dma_read(), i2c_imx_read() and i2c_imx_xfer(). Signed-off-by: Esben Haabendal Acked-by: Uwe Kleine-König Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-imx.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) (limited to 'drivers/i2c/busses/i2c-imx.c') diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index eb11ac3d6aba..7029542c75fb 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -420,10 +420,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy) return -EAGAIN; } - if (for_busy && (temp & I2SR_IBB)) + if (for_busy && (temp & I2SR_IBB)) { + i2c_imx->stopped = 0; break; - if (!for_busy && !(temp & I2SR_IBB)) + } + if (!for_busy && !(temp & I2SR_IBB)) { + i2c_imx->stopped = 1; break; + } if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) { dev_dbg(&i2c_imx->adapter.dev, "<%s> I2C bus is busy\n", __func__); @@ -537,7 +541,6 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx) result = i2c_imx_bus_busy(i2c_imx, 1); if (result) return result; - i2c_imx->stopped = 0; temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK; temp &= ~I2CR_DMAEN; @@ -566,10 +569,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx) udelay(i2c_imx->disable_delay); } - if (!i2c_imx->stopped) { + if (!i2c_imx->stopped) i2c_imx_bus_busy(i2c_imx, 0); - i2c_imx->stopped = 1; - } /* Disable I2C controller */ temp = i2c_imx->hwdata->i2cr_ien_opcode ^ I2CR_IEN, @@ -725,7 +726,6 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx, temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); i2c_imx_bus_busy(i2c_imx, 0); - i2c_imx->stopped = 1; } else { /* * For i2c master receiver repeat restart operation like: @@ -851,7 +851,6 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo temp &= ~(I2CR_MSTA | I2CR_MTX); imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); i2c_imx_bus_busy(i2c_imx, 0); - i2c_imx->stopped = 1; } else { /* * For i2c master receiver repeat restart operation like: -- cgit v1.2.3