On Mon, May 08, 2017 at 02:44:25PM -0700, Guenter Roeck wrote: > On Mon, May 08, 2017 at 02:10:31PM -0700, Dmitry Torokhov wrote: > > On Wed, May 03, 2017 at 11:42:54PM -0700, Guenter Roeck wrote: > > > On 05/03/2017 11:29 PM, Dmitry Torokhov wrote: > > > >Before trying to properly initialize the touchpad and generate bunch of > > > >errors, let's first see it there is anything at the given address. If we > > > >get error, fail silently with -ENXIO. > > > > > > > >Signed-off-by: Dmitry Torokhov <[email protected]> > > > >--- > > > > drivers/input/mouse/elan_i2c_core.c | 9 +++++++++ > > > > 1 file changed, 9 insertions(+) > > > > > > > >diff --git a/drivers/input/mouse/elan_i2c_core.c > > > >b/drivers/input/mouse/elan_i2c_core.c > > > >index 5d3b53dd2fa2..0479730e7c5c 100644 > > > >--- a/drivers/input/mouse/elan_i2c_core.c > > > >+++ b/drivers/input/mouse/elan_i2c_core.c > > > >@@ -1040,6 +1040,7 @@ static int elan_probe(struct i2c_client *client, > > > > const struct elan_transport_ops *transport_ops; > > > > struct device *dev = &client->dev; > > > > struct elan_tp_data *data; > > > >+ union i2c_smbus_data dummy; > > > > unsigned long irqflags; > > > > int error; > > > > > > > >@@ -1091,6 +1092,14 @@ static int elan_probe(struct i2c_client *client, > > > > return error; > > > > } > > > > > > > >+ /* Make sure there is something at this address */ > > > >+ error = i2c_smbus_xfer(client->adapter, client->addr, 0, > > > >+ I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, > > > >&dummy); > > > > > > Can't you just call i2c_smbus_read_byte_data(client, 0); and check if it > > > returns > > > an error ? > > > > Are we guaranteed to get a result from command "0"? I am not sure, and > > looking at least at i2c_smbus_xfer_emulated() I2C_SMBUS_READ with > > I2C_SMBUS_BYTE modifier works differently form > > I2C_SMBUS_READ/I2C_SMBUS_BYTE_DATA (the former uses a single i2c message > > vs 2 for the latter). > > > > Also the form above is what i2c core uses to do detection when adapter > > does not implement I2C_SMBUS_QUICK, so I'd rather leave it as it was. > > > > How about i2c_smbus_read_byte() ? > > status = i2c_smbus_xfer(client->adapter, client->addr, client->flags, > I2C_SMBUS_READ, 0, > I2C_SMBUS_BYTE, &data); > return (status < 0) ? status : data.byte;
Yeah, I think this will work. Thanks. -- Dmitry
