mec1322: i2c: Unwedge controller on transaction timeout

If clk or dat aren't pulled up for an extended period, the i2c
controller may get into a wedged state that requires a controller reset
to recover from. There are no outward signs of the controller being in
such a state, other than transaction timeouts. Therefore, on a
transaction timeout, reset the controller.

BUG=chrome-os-partner:43270
TEST=Manual on glados:
- Run `gpioset PP3300_USB_PD_EN 0` on PD console and wait several seconds
- Run `gpioset PP3300_USB_PD_EN 1` on PD console
- Run `i2cscan` and verify all ports / devices ack
- Repeat above several times
BRANCH=None

Change-Id: I2ae42762ee6c961224ff50309a448475b67854b5
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/295404
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
(cherry picked from commit d43ced8c8de8eecc4850b6c346b43774ff3e3ba9)

BUG=chrome-os-partner: 
TEST=Manual on celes:46863
- Ground I2C0_0_DAT line manually 
- After release this line, see i2C line is working again.
- Run `i2cscan` and verify all ports / devices ack

Change-Id: Ie9a860728e8f91a949ca61be4fe5294277b1d3f4
Reviewed-on: https://chromium-review.googlesource.com/308967
Reviewed-by: Shawn N <shawnn@chromium.org>
Commit-Queue: Wonjoon Lee <woojoo.lee@samsung.com>
Tested-by: Wonjoon Lee <woojoo.lee@samsung.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/chip/mec1322/i2c.c b/chip/mec1322/i2c.c
index 36ecabdbc4..4ef54a2dd4 100644
--- a/chip/mec1322/i2c.c
+++ b/chip/mec1322/i2c.c
@@ -369,8 +369,16 @@ err_chip_i2c_xfer:
 				       CTRL_STO | CTRL_ACK;
 	if (ret_done == STS_LRB)
 		return EC_ERROR_BUSY;
-	else if (ret_done == EC_ERROR_TIMEOUT)
+	else if (ret_done == EC_ERROR_TIMEOUT) {
+		/*
+		 * If our transaction timed out then our i2c controller
+		 * may be wedged without showing any other outward signs
+		 * of failure. Reset the controller so that future
+		 * transactions have a chance of success.
+		 */
+		reset_controller(controller);
 		return EC_ERROR_TIMEOUT;
+	}
 	else
 		return EC_ERROR_UNKNOWN;
 }