diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2016-12-17 12:10:56 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-19 20:18:05 +0100 |
| commit | 26eae206b78669ec4994d047a4b9418b1c588e35 (patch) | |
| tree | 75200eb54e7f7f5914eec154a499a216d8f71334 | |
| parent | 396b25173370fc1afa3bc91a315d5597c2b10734 (diff) | |
i2c: mux: pca954x: fix i2c mux selection caching
commit 7f638c1cb0a1112dbe0b682a42db30521646686b upstream.
smbus functions return -ve on error, 0 on success. However,
__i2c_transfer() have a different return signature - -ve on error, or
number of buffers transferred (which may be zero or greater.)
The upshot of this is that the sense of the test is reversed when using
the mux on a bus supporting the master_xfer method: we cache the value
and never retry if we fail to transfer any buffers, but if we succeed,
we clear the cached value.
Fix this by making pca954x_reg_write() return a negative error code for
all failure cases.
Fixes: 463e8f845cbf ("i2c: mux: pca954x: retry updating the mux selection on failure")
Acked-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/i2c/muxes/i2c-mux-pca954x.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c index 8bc3d36d2837..9c4ac26c014e 100644 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c @@ -151,6 +151,9 @@ static int pca954x_reg_write(struct i2c_adapter *adap, buf[0] = val; msg.buf = buf; ret = __i2c_transfer(adap, &msg, 1); + + if (ret >= 0 && ret != 1) + ret = -EREMOTEIO; } else { union i2c_smbus_data data; ret = adap->algo->smbus_xfer(adap, client->addr, @@ -179,7 +182,7 @@ static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan) /* Only select the channel if its different from the last channel */ if (data->last_chan != regval) { ret = pca954x_reg_write(muxc->parent, client, regval); - data->last_chan = ret ? 0 : regval; + data->last_chan = ret < 0 ? 0 : regval; } return ret; |