openwrt/target/linux/layerscape/patches-5.4/808-i2c-0007-i2c-imx-add-workaround-for-erratum-ERR010027.patch

From 8e7e594b685f3fe44cd4803e3a4634bed897c2f7 Mon Sep 17 00:00:00 2001
From: Zhang Ying-22455 <ying.zhang22455@nxp.com>
Date: Fri, 14 Apr 2017 17:03:03 +0800
Subject: [PATCH] i2c: imx: add workaround for erratum ERR010027

ERR010027: Attempting a start cycle while the bus is busy may
generate a short clock pulse.

Software must ensure that the I2C BUS is idle by checking the
bus busy before switching to master mode and attempting a Start
cycle.

Signed-off-by: Zhang Ying-22455 <ying.zhang22455@nxp.com>
---
 drivers/i2c/busses/i2c-imx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -940,6 +940,14 @@ static int i2c_imx_xfer(struct i2c_adapt
 		enable_runtime_pm = true;
 	}
 
+	/*
+	 * workround for ERR010027: ensure that the I2C BUS is idle
+	 * before switching to master mode and attempting a Start cycle
+	 */
+	result =  i2c_imx_bus_busy(i2c_imx, 0);
+	if (result)
+		goto out;
+
 	result = pm_runtime_get_sync(i2c_imx->adapter.dev.parent);
 	if (result < 0)
 		goto out;