From c5b4afec8e669bbe265daea24037fccfc42c4fe3 Mon Sep 17 00:00:00 2001 From: Jon Povey Date: Tue, 12 Oct 2010 13:47:05 +0900 Subject: i2c-davinci: Fix TX setup for more SoCs This patch is an improvement to 4bba0fd8d1c6d405df666e2573e1a1f917098be0 which got to mainline a little early. Sudhakar Rajashekhara explains that at least OMAP-L138 requires MDR mode settings before DXR for correct behaviour, so load MDR first with STT cleared and later load again with STT set. Tested on DM355 connected to Techwell TW2836 and Wolfson WM8985 Signed-off-by: Jon Povey Acked-by: Troy Kisky Tested-by: Sudhakar Rajashekhara Acked-by: Kevin Hilman Signed-off-by: Ben Dooks --- drivers/i2c/busses/i2c-davinci.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c index b8feac5f2ef4..5795c8398c7c 100644 --- a/drivers/i2c/busses/i2c-davinci.c +++ b/drivers/i2c/busses/i2c-davinci.c @@ -331,21 +331,16 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) INIT_COMPLETION(dev->cmd_complete); dev->cmd_err = 0; - /* Take I2C out of reset, configure it as master and set the - * start bit */ - flag = DAVINCI_I2C_MDR_IRS | DAVINCI_I2C_MDR_MST | DAVINCI_I2C_MDR_STT; + /* Take I2C out of reset and configure it as master */ + flag = DAVINCI_I2C_MDR_IRS | DAVINCI_I2C_MDR_MST; /* if the slave address is ten bit address, enable XA bit */ if (msg->flags & I2C_M_TEN) flag |= DAVINCI_I2C_MDR_XA; if (!(msg->flags & I2C_M_RD)) flag |= DAVINCI_I2C_MDR_TRX; - if (stop) - flag |= DAVINCI_I2C_MDR_STP; - if (msg->len == 0) { + if (msg->len == 0) flag |= DAVINCI_I2C_MDR_RM; - flag &= ~DAVINCI_I2C_MDR_STP; - } /* Enable receive or transmit interrupts */ w = davinci_i2c_read_reg(dev, DAVINCI_I2C_IMR_REG); @@ -357,18 +352,29 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) dev->terminate = 0; + /* + * Write mode register first as needed for correct behaviour + * on OMAP-L138, but don't set STT yet to avoid a race with XRDY + * occuring before we have loaded DXR + */ + davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); + /* * First byte should be set here, not after interrupt, * because transmit-data-ready interrupt can come before * NACK-interrupt during sending of previous message and * ICDXR may have wrong data + * It also saves us one interrupt, slightly faster */ if ((!(msg->flags & I2C_M_RD)) && dev->buf_len) { davinci_i2c_write_reg(dev, DAVINCI_I2C_DXR_REG, *dev->buf++); dev->buf_len--; } - /* write the data into mode register; start transmitting */ + /* Set STT to begin transmit now DXR is loaded */ + flag |= DAVINCI_I2C_MDR_STT; + if (stop && msg->len != 0) + flag |= DAVINCI_I2C_MDR_STP; davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag); r = wait_for_completion_interruptible_timeout(&dev->cmd_complete, -- cgit v1.2.2 From e39428d53d080ad2615b772d7f99d2a70c2aaab2 Mon Sep 17 00:00:00 2001 From: Marc Kleine-Budde Date: Mon, 21 Jun 2010 09:27:05 +0200 Subject: i2c-imx: do not allow interruptions when waiting for I2C to complete The i2c_imx_trx_complete() function is using wait_event_interruptible_timeout() to wait for the I2C controller to signal that it has completed an I2C bus operation. If the process that causes the I2C operation receives a signal, the wait will be interrupted, returning an error. It is better to let the I2C operation finished before handling the signal (i.e. returning into userspace). It is safe to use wait_event_timeout() instead, because the timeout will allow the process to exit if the I2C bus hangs. It's also better to allow the I2C operation to finish, because unacknowledged I2C operations can cause the I2C bus to hang. Signed-off-by: Marc Kleine-Budde Reviewed-by: Wolfram Sang Signed-off-by: Ben Dooks --- drivers/i2c/busses/i2c-imx.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index d1ff9408dc1f..4c2a62b75b5c 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -159,15 +159,9 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy) static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx) { - int result; - - result = wait_event_interruptible_timeout(i2c_imx->queue, - i2c_imx->i2csr & I2SR_IIF, HZ / 10); + wait_event_timeout(i2c_imx->queue, i2c_imx->i2csr & I2SR_IIF, HZ / 10); - if (unlikely(result < 0)) { - dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__); - return result; - } else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) { + if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) { dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__); return -ETIMEDOUT; } @@ -295,7 +289,7 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id) i2c_imx->i2csr = temp; temp &= ~I2SR_IIF; writeb(temp, i2c_imx->base + IMX_I2C_I2SR); - wake_up_interruptible(&i2c_imx->queue); + wake_up(&i2c_imx->queue); return IRQ_HANDLED; } -- cgit v1.2.2