[PATCH 3.16 314/346] i2c: mux: pca954x: retry updating the mux selection on failure

[Ben Hutchings]

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Rosin <peda@xxxxxxxxxx>

commit 463e8f845cbf1c01e4cc8aeef1703212991d8e1e upstream.

The cached value of the last selected channel prevents retries on the
next call, even on failure to update the selected channel. Fix that.

Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/i2c/muxes/i2c-mux-pca954x.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -161,7 +161,7 @@ static int pca954x_select_chan(struct i2
 	/* Only select the channel if its different from the last channel */
 	if (data->last_chan != regval) {
 		ret = pca954x_reg_write(adap, client, regval);
-		data->last_chan = regval;
+		data->last_chan = ret ? 0 : regval;
 	}
 
 	return ret;