[PATCH v2] i2c: xiic: improve error message when transfer fails to start

[marc.ferland@gmail.com]

From: Marc Ferland <marc.ferland@sonatest.com>

xiic_start_xfer can fail for different reasons:

- EBUSY: bus is busy or i2c messages still in tx_msg or rx_msg
- ETIMEDOUT: timed-out trying to clear the RX fifo
- EINVAL: wrong clock settings

Both EINVAL and ETIMEDOUT will currently print a specific error
message followed by a generic one, for example:

    Failed to clear rx fifo
    Error xiic_start_xfer

however EBUSY will simply output the generic message:

    Error xiic_start_xfer

which is not really helpful.

This commit adds a new error message when a busy condition is detected
and also removes the generic message since it does not provide any
relevant information to the user.

Signed-off-by: Marc Ferland <marc.ferland@sonatest.com>
---
Changes in v2:
 - add a message where the error actually occurs (suggested by
   Andi Shyti)
 - remove the generic message completely (Andi Shyti)

 drivers/i2c/busses/i2c-xiic.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index b9ad935d7ff3..afb242be456d 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -1114,8 +1114,11 @@ static int xiic_start_xfer(struct xiic_i2c *i2c, struct i2c_msg *msgs, int num)
 	mutex_lock(&i2c->lock);
 
 	ret = xiic_busy(i2c);
-	if (ret)
+	if (ret) {
+		dev_err(i2c->adap.dev.parent,
+			"cannot start a transfer while busy\n");
 		goto out;
+	}
 
 	i2c->tx_msg = msgs;
 	i2c->rx_msg = NULL;
@@ -1173,10 +1176,8 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 		return err;
 
 	err = xiic_start_xfer(i2c, msgs, num);
-	if (err < 0) {
-		dev_err(adap->dev.parent, "Error xiic_start_xfer\n");
+	if (err < 0)
 		goto out;
-	}
 
 	err = wait_for_completion_timeout(&i2c->completion, XIIC_XFER_TIMEOUT);
 	mutex_lock(&i2c->lock);
-- 
2.34.1