From: Haibo Chen <haibo.chen@xxxxxxxxxxxxx> Sent: Monday, September 01, 2014 4:59 PM
>To: wsa@xxxxxxxxxxxxx
>Cc: linux-i2c@xxxxxxxxxxxxxxx; Duan Fugang-B38611
>Subject: [PATCH] i2c: imx: Add arbitration lost check
>
>According to the i.mx spec, for multimaster mode, if I2C is enabled when
>the bus is busy and asserts start, hardware inhibits the transmission,
>clears MSTA without signaling a stop, generate an interrupt, and set
>I2C_I2SR[IAL] to indicate a failed attempt to engage the bus, which means
>arbitration lost. In this case, we should first test I2C_I2SR[IAL], and
>clear this bit if it is set, and then I2C controller default to slave
>receive mode.
>
>This patch check the IAL bit every time before an I2c transmission.
>if IAL is set, clear it and make I2C controller to default mode.
>
>Signed-off-by: Haibo Chen <haibo.chen@xxxxxxxxxxxxx>
>---
> drivers/i2c/busses/i2c-imx.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
>diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>index 613069b..144b620 100644
>--- a/drivers/i2c/busses/i2c-imx.c
>+++ b/drivers/i2c/busses/i2c-imx.c
>@@ -268,6 +268,14 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct
>*i2c_imx, int for_busy)
>
> while (1) {
> temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
>+
>+ /** check for arbitration lost **/
>+ if (temp & I2SR_IAL) {
>+ temp &= ~I2SR_IAL;
>+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
>+ return -EIO;
>+ }
>+
> if (for_busy && (temp & I2SR_IBB))
> break;
> if (!for_busy && !(temp & I2SR_IBB))
>--
>1.9.1
Acked-by: Fugang Duan <B38611@xxxxxxxxxxxxx>
Thanks,
Andy
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