From b8dcb812401026cb2189b24a4f6058830151c85a Mon Sep 17 00:00:00 2001 From: Fugang Duan Date: Mon, 11 Aug 2014 15:14:50 +0800 Subject: ENGR00328312 i2c: imx: Optimize the i2c device recovery solution From i2c spec, if device pull down the SDA line that causes i2c bus dead, host can send out 9 clock to let device release SDA. But for some special device like pfuze100, it pull down SDA line and the solution cannot take effort. The patch just add NACK and STOP signal after 8 dummy clock, and pmic can release SDA line after the recovery. Test case catch 375 times of i2c hang, and all are recovered. Signed-off-by: Fugang Duan (cherry picked from commit 53118db42d201d36ca9067b4bb0e2702399e100b) Signed-off-by: Peng Fan --- arch/arm/imx-common/i2c-mxv7.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) (limited to 'arch/arm') diff --git a/arch/arm/imx-common/i2c-mxv7.c b/arch/arm/imx-common/i2c-mxv7.c index 1a632e7..b1d4ec4 100644 --- a/arch/arm/imx-common/i2c-mxv7.c +++ b/arch/arm/imx-common/i2c-mxv7.c @@ -33,13 +33,36 @@ static int force_idle_bus(void *priv) printf("%s: sda=%d scl=%d sda.gp=0x%x scl.gp=0x%x\n", __func__, sda, scl, p->sda.gp, p->scl.gp); + gpio_direction_output(p->scl.gp, 1); + udelay(1000); /* Send high and low on the SCL line */ for (i = 0; i < 9; i++) { - gpio_direction_output(p->scl.gp, 0); + gpio_direction_output(p->scl.gp, 1); udelay(50); - gpio_direction_input(p->scl.gp); + gpio_direction_output(p->scl.gp, 0); udelay(50); } + + /* Simulate the NACK */ + gpio_direction_output(p->sda.gp, 1); + udelay(50); + gpio_direction_output(p->scl.gp, 1); + udelay(50); + gpio_direction_output(p->scl.gp, 0); + udelay(50); + + /* Simulate the STOP signal */ + gpio_direction_output(p->sda.gp, 0); + udelay(50); + gpio_direction_output(p->scl.gp, 1); + udelay(50); + gpio_direction_output(p->sda.gp, 1); + udelay(50); + + /* Get the bus status */ + gpio_direction_input(p->sda.gp); + gpio_direction_input(p->scl.gp); + start_time = get_timer(0); for (;;) { sda = gpio_get_value(p->sda.gp); -- cgit v1.1