From 7d054817b780e664bed6701b2aa637718e1905b7 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Tue, 1 May 2007 23:26:33 +0200 Subject: i2c-pxa: Clean transaction stop It was reported to me that the i2c-pxa driver was not able to process more that 50 transactions per second. Investigation revealed that the I2C unit was busy for 20 ms after every transaction. The reason seems to be that we forget to clear the STOP and ACKNACK bits at the end of the transaction. According to the PXA27x developer's manual, we shall do so. Signed-off-by: Jean Delvare Cc: Lennert Buytenhek Cc: Nicolas Pitre --- drivers/i2c/busses/i2c-pxa.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'drivers/i2c') diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c index 14e83d0..2fc3bce 100644 --- a/drivers/i2c/busses/i2c-pxa.c +++ b/drivers/i2c/busses/i2c-pxa.c @@ -539,6 +539,18 @@ static inline void i2c_pxa_start_message(struct pxa_i2c *i2c) writel(icr | ICR_START | ICR_TB, _ICR(i2c)); } +static inline void i2c_pxa_stop_message(struct pxa_i2c *i2c) +{ + u32 icr; + + /* + * Clear the STOP and ACK flags + */ + icr = readl(_ICR(i2c)); + icr &= ~(ICR_STOP | ICR_ACKNAK); + writel(icr, _IRC(i2c)); +} + /* * We are protected by the adapter bus mutex. */ @@ -581,6 +593,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c *i2c, struct i2c_msg *msg, int num) * The rest of the processing occurs in the interrupt handler. */ timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5); + i2c_pxa_stop_message(i2c); /* * We place the return code in i2c->msg_idx. -- cgit v1.1