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 <dmitry.torokhov@xxxxxxxxx> > >--- > > 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. Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
