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 <yamada.masahiro@socionext.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c
index 829df91cc75966453d25184dafabc1f21ecd99f1..db9105e52c79a1ad7ba0c9b867a617244f40b874 100644 (file)
--- 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;
                }
        }