i2c: designware: report short transfers

Rather than reporting success for a short transfer due to interrupt
latency, report an error both to the caller, as well as to the kernel
log.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 11e866d05368..066a2ba6aeda 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -758,7 +758,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
         }
 
         /* no error */
-        if (likely(!dev->cmd_err)) {
+        if (likely(!dev->cmd_err && !dev->status)) {
                 ret = num;
                 goto done;
         }
@@ -768,6 +768,11 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
                 ret = i2c_dw_handle_tx_abort(dev);
                 goto done;
         }
+
+        if (dev->status)
+                dev_err(dev->dev,
+                        "transfer terminated early - interrupt latency too high?\n");
+
         ret = -EIO;
 
 done: