[PATCH 03/12] i2c: pxa: Add reset operation when i2c bus busy

Vaibhav Hiremath vaibhav.hiremath at linaro.org
Thu May 28 06:03:35 PDT 2015

From: "Jett.Zhou" <jtzhou at marvell.com>

According to some test in emei_dkb, we found some i2c slave device
(eg. camera sensor ov2659 power up) introduce noise on sda, so detect
i2c controller busy, and assert reset to i2c controller to recover as
early as possible to avoid more latency on the entire i2c transaction.

Signed-off-by: Jett.Zhou <jtzhou at marvell.com>
[vaibhav.hiremath at linaro.org: Removed reduction in timeout value, as I
do not have goot explanation for it. Logically it is not required.
And also Updated changelog]
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath at linaro.org>

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath at linaro.org>
 drivers/i2c/busses/i2c-pxa.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index d4c798a..a76c901 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -314,6 +314,10 @@ static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
 	int timeout = DEF_TIMEOUT;
+	if (readl(_ISR(i2c)) & (ISR_IBB | ISR_UB))
+		i2c_pxa_reset(i2c);
 	while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
 		if ((readl(_ISR(i2c)) & ISR_SAD) != 0)
 			timeout += 4;

More information about the linux-arm-kernel mailing list