-----Original Message----- From: linux-i2c-owner@xxxxxxxxxxxxxxx [mailto:linux-i2c-owner@xxxxxxxxxxxxxxx] On Behalf Of Shinya Kuribayashi Sent: Monday, October 12, 2009 9:53 PM To: baruch@xxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx Cc: ben-linux@xxxxxxxxx; linux-mips@xxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx Subject: [PATCH 12/16] 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 the slave address and enable the DW I2C core. It's executed only when we don't have STATUS_WRITE_IN_PROGRESS. Then 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 the 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 == Tx FIFO depth). Consequently we should not use STATUS_WRITE_IN_PROGRESS to determine where we're at in the I2C transaction, then let's separate those initialization steps from i2c_dw_xfer_msg(). Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi@xxxxxxxxx> --- drivers/i2c/busses/i2c-designware.c | 45 +++++++++++++++++++--------------- 1 files changed, 25 insertions(+), 20 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware.c b/drivers/i2c/busses/i2c-designware.c index d9b5790..de006f0 100644 --- a/drivers/i2c/busses/i2c-designware.c +++ b/drivers/i2c/busses/i2c-designware.c @@ -325,6 +325,29 @@ 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. @@ -335,31 +358,12 @@ 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; u32 buf_len = dev->tx_buf_len; - 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 */ -- 1.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
