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[1/2] i2c: rcar: improve bus busy detection

Message ID 20200829203810.1467-2-wsa+renesas@sang-engineering.com
State Accepted
Commit 9374ed1dfe1f862f6dd7552b8164252fe5cc424f
Headers show
Series [1/2] i2c: rcar: improve bus busy detection | expand

Commit Message

Wolfram Sang Aug. 29, 2020, 8:38 p.m. UTC
I2C doesn't define a timeout for bus busy, so an arbitrary value like
LOOP_TIMEOUT is not a good idea. Let's use the timeout value in struct
adapter which is meant for such cases and is user-configurable (via
IOCTL). To reduce the load, wait 10us instead of 1us which is good
enough for the slow frequencies used by I2C. Finally, use the
poll_timeout helper instead of open coding it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/i2c/busses/i2c-rcar.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)
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Patch

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 0f73f0681a6e..ef10514f6215 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -19,6 +19,7 @@ 
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/i2c.h>
 #include <linux/i2c-smbus.h>
 #include <linux/kernel.h>
@@ -225,18 +226,18 @@  static void rcar_i2c_init(struct rcar_i2c_priv *priv)
 
 static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
 {
-	int i;
+	int ret;
+	u32 val;
 
-	for (i = 0; i < LOOP_TIMEOUT; i++) {
-		/* make sure that bus is not busy */
-		if (!(rcar_i2c_read(priv, ICMCR) & FSDA))
-			return 0;
-		udelay(1);
+	ret = readl_poll_timeout(priv->io + ICMCR, val, !(val & FSDA), 10,
+				 priv->adap.timeout);
+	if (ret) {
+		/* Waiting did not help, try to recover */
+		priv->recovery_icmcr = MDBS | OBPC | FSDA | FSCL;
+		ret = i2c_recover_bus(&priv->adap);
 	}
 
-	/* Waiting did not help, try to recover */
-	priv->recovery_icmcr = MDBS | OBPC | FSDA | FSCL;
-	return i2c_recover_bus(&priv->adap);
+	return ret;
 }
 
 static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)