From 0c25aefa35c2fb5592895615f77d9f6fa36a849d Mon Sep 17 00:00:00 2001 From: Joakim Tjernlund Date: Thu, 30 Aug 2012 12:40:04 +0200 Subject: [PATCH] i2c: mpc: Wait for STOP to hit the bus mpc_i2c_stop() only initiates STOP but does not wait for it to hit the I2C bus. This is a problem when using I2C devices which uses fairly long clock stretching just before STOP if you also have an i2c-mux which may switch to another bus before STOP has been processed. Signed-off-by: Joakim Tjernlund Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-mpc.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index b76731e..64b0b4d 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -576,7 +576,23 @@ static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i); } } - mpc_i2c_stop(i2c); + mpc_i2c_stop(i2c); /* Initiate STOP */ + orig_jiffies = jiffies; + /* Wait until STOP is seen, allow up to 1 s */ + while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) { + if (time_after(jiffies, orig_jiffies + HZ)) { + u8 status = readb(i2c->base + MPC_I2C_SR); + + dev_dbg(i2c->dev, "timeout\n"); + if ((status & (CSR_MCF | CSR_MBB | CSR_RXAK)) != 0) { + writeb(status & ~CSR_MAL, + i2c->base + MPC_I2C_SR); + mpc_i2c_fixup(i2c); + } + return -EIO; + } + cond_resched(); + } return (ret < 0) ? ret : num; } -- 2.7.4