i2c: uniphier-f: fix misdetection of incomplete STOP condition

Currently, the status register FI2C_SR is checked immediately after a STOP condition is issued in case of the deferred STOP condition. It takes typically 5-10 usec until the corresponding bits in the register are set, so the error check for "stop condition was not completed" is very likely to be false positive. Add wait code to relax the status register check. Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Wolfram Sang <[email protected]>
jledet · Sep 24, 2016 · fcbd4bd · fcbd4bd
1 parent 6212e1d
commit fcbd4bd
Showing 1 changed file with 11 additions and 5 deletions.
diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c
@@ -14,6 +14,7 @@
 
 #include <linux/clk.h>
 #include <linux/i2c.h>
+#include <linux/iopoll.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
@@ -348,14 +349,19 @@ static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap,
 	dev_dbg(&adap->dev, "complete\n");
 
 	if (unlikely(priv->flags & UNIPHIER_FI2C_DEFER_STOP_COMP)) {
-		u32 status = readl(priv->membase + UNIPHIER_FI2C_SR);
-
-		if (!(status & UNIPHIER_FI2C_SR_STS) ||
-		    status & UNIPHIER_FI2C_SR_BB) {
+		u32 status;
+		int ret;
+
+		ret = readl_poll_timeout(priv->membase + UNIPHIER_FI2C_SR,
+					 status,
+					 (status & UNIPHIER_FI2C_SR_STS) &&
+					 !(status & UNIPHIER_FI2C_SR_BB),
+					 1, 20);
+		if (ret) {
 			dev_err(&adap->dev,
 				"stop condition was not completed.\n");
 			uniphier_fi2c_recover(priv);
-			return -EBUSY;
+			return ret;
 		}
 	}