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i2c: mux: mlxcpld: fix i2c mux selection caching 

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 mlxcpld_mux_reg_write() return a -ve error code for
all failure cases, just as was done in commit 7f638c1cb0 ("i2c: mux:
pca954x: fix i2c mux selection caching").

This also aligns the implementations of these two muxes in this area.

Signed-off-by: Peter Rosin <peda@axentia.se>
Acked-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Peter Rosin 2016-12-17 21:29:11 +01:00 committed by Wolfram Sang
parent 8e598769c5
commit 649ac63a9a
1 changed files with 13 additions and 11 deletions
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18
drivers/i2c/muxes/i2c-mux-mlxcpld.c
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@ -95,6 +95,7 @@ static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
struct i2c_client *client, u8 val)
{
struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
int ret = -ENODEV;
if (adap->algo->master_xfer) {
struct i2c_msg msg;
@ -104,17 +105,21 @@ static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
msg.flags = 0;
msg.len = 2;
msg.buf = msgbuf;
return __i2c_transfer(adap, &msg, 1);
ret = __i2c_transfer(adap, &msg, 1);
if (ret >= 0 && ret != 1)
ret = -EREMOTEIO;
} else if (adap->algo->smbus_xfer) {
union i2c_smbus_data data;
data.byte = val;
return adap->algo->smbus_xfer(adap, client->addr,
ret = adap->algo->smbus_xfer(adap, client->addr,
client->flags, I2C_SMBUS_WRITE,
pdata->sel_reg_addr,
I2C_SMBUS_BYTE_DATA, &data);
} else
return -ENODEV;
}
return ret;
}
static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
@ -127,10 +132,7 @@ static int mlxcpld_mux_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) {
err = mlxcpld_mux_reg_write(muxc->parent, client, regval);
if (err)
data->last_chan = 0;
else
data->last_chan = regval;
data->last_chan = err < 0 ? 0 : regval;
}
return err;