From 81e798b73aec2d7ce06d18bd191b088c233e554f Mon Sep 17 00:00:00 2001 From: Shinya Kuribayashi Date: Fri, 6 Nov 2009 21:48:55 +0900 Subject: [PATCH] i2c-designware: Divide i2c_dw_xfer_msg into two functions We have some steps at the top of i2c_dw_xfer_msg() to set up a slave address and enable DW I2C core. And it's executed only when we don't have STATUS_WRITE_IN_PROGRESS. But we need to make sure that STATUS_WRITE_IN_PROGRESS only indicates that we have a pending i2c_msg to process. In other words, even if STATUS_WRITE_IN_PROGRESS is not set, that doesn't mean we're at initial state in the I2C transaction. Since i2c_dw_xfer_msg() will be invoked again and again during a transaction, those init steps have a possibility to be re-processed needlessly. For example, this issue easily takes place when processing a combined transaction with a certain condition (the number of tx bytes in the first i2c_msg, equals to the Tx FIFO depth). Consequently we should not use STATUS_WRITE_IN_PROGRESS to determine where we're at in an I2C transaction. It would be better to separate those initialization steps from i2c_dw_xfer_msg(). Signed-off-by: Shinya Kuribayashi Acked-by: Baruch Siach Signed-off-by: Ben Dooks --- drivers/i2c/busses/i2c-designware.c | 45 ++++++++++++++++------------- 1 file changed, 25 insertions(+), 20 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware.c b/drivers/i2c/busses/i2c-designware.c index 940bbf31bc8c..da5612b21aff 100644 --- a/drivers/i2c/busses/i2c-designware.c +++ b/drivers/i2c/busses/i2c-designware.c @@ -326,6 +326,29 @@ static int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev) return 0; } +static void i2c_dw_xfer_init(struct dw_i2c_dev *dev) +{ + struct i2c_msg *msgs = dev->msgs; + u32 ic_con; + + /* Disable the adapter */ + writel(0, dev->base + DW_IC_ENABLE); + + /* set the slave (target) address */ + writel(msgs[dev->msg_write_idx].addr, dev->base + DW_IC_TAR); + + /* if the slave address is ten bit address, enable 10BITADDR */ + ic_con = readl(dev->base + DW_IC_CON); + if (msgs[dev->msg_write_idx].flags & I2C_M_TEN) + ic_con |= DW_IC_CON_10BITADDR_MASTER; + else + ic_con &= ~DW_IC_CON_10BITADDR_MASTER; + writel(ic_con, dev->base + DW_IC_CON); + + /* Enable the adapter */ + writel(1, dev->base + DW_IC_ENABLE); +} + /* * Initiate low level master read/write transaction. * This function is called from i2c_dw_xfer when starting a transfer. @@ -336,7 +359,7 @@ static void i2c_dw_xfer_msg(struct dw_i2c_dev *dev) { struct i2c_msg *msgs = dev->msgs; - u32 ic_con, intr_mask; + u32 intr_mask; int tx_limit = dev->tx_fifo_depth - readl(dev->base + DW_IC_TXFLR); int rx_limit = dev->rx_fifo_depth - readl(dev->base + DW_IC_RXFLR); u32 addr = msgs[dev->msg_write_idx].addr; @@ -344,25 +367,6 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev) intr_mask = DW_IC_INTR_STOP_DET | DW_IC_INTR_TX_ABRT | DW_IC_INTR_RX_FULL; - if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) { - /* Disable the adapter */ - writel(0, dev->base + DW_IC_ENABLE); - - /* set the slave (target) address */ - writel(msgs[dev->msg_write_idx].addr, dev->base + DW_IC_TAR); - - /* if the slave address is ten bit address, enable 10BITADDR */ - ic_con = readl(dev->base + DW_IC_CON); - if (msgs[dev->msg_write_idx].flags & I2C_M_TEN) - ic_con |= DW_IC_CON_10BITADDR_MASTER; - else - ic_con &= ~DW_IC_CON_10BITADDR_MASTER; - writel(ic_con, dev->base + DW_IC_CON); - - /* Enable the adapter */ - writel(1, dev->base + DW_IC_ENABLE); - } - for (; dev->msg_write_idx < dev->msgs_num; dev->msg_write_idx++) { /* if target address has changed, we need to * reprogram the target address in the i2c @@ -474,6 +478,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) goto done; /* start the transfers */ + i2c_dw_xfer_init(dev); i2c_dw_xfer_msg(dev); /* wait for tx to complete */ -- 2.20.1