| Message ID | E1cIDpI-0005y4-SW@rmk-PC.armlinux.org.uk |
|---|---|
| State | Accepted |
| Headers | show |
On Sat, Dec 17, 2016 at 12:10:56PM +0000, Russell King wrote: > 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> Applied to for-current, thanks!
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;
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> --- drivers/i2c/muxes/i2c-mux-pca954x.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)