On Thu, 2014-12-18 at 17:28 +0100, Lars-Peter Clausen wrote: > Added I2C to Cc. > > On 12/15/2014 10:19 PM, Srinivas Pandruvada wrote: > > Using i2c auto detect feature and auto device creation feature, > > enumerate ak8975 device, by checking their presence. > > This is needed because when this device sits behind an i2c mux, there > > is no way to define i2c mux in ACPI. This will enable ak8975 on > > windows based tablets/laptops running Linux when connected via a mux. > > Since DT model already can define an i2c mux and devices connected to > > it, this feature is only enabled for ACPI. > > > > This is quite a bit of a hack. Why? Auto detect is standard feature of i2c devices. This is using standard auto detect feature provided by the framework. > Did they decide to not include the device in > the ACPI description at all or is there a special id for INV6050+AK8975? This device needs has one combined id. Windows has a singe driver processing both as a combo device. > > How does Windows decide whether there is a device or not? > > Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> > > --- > > drivers/iio/magnetometer/ak8975.c | 35 +++++++++++++++++++++++++++++++++++ > > 1 file changed, 35 insertions(+) > > > > diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c > > index 0d10a4b..c3455bd 100644 > > --- a/drivers/iio/magnetometer/ak8975.c > > +++ b/drivers/iio/magnetometer/ak8975.c > > @@ -820,6 +820,36 @@ static const struct i2c_device_id ak8975_id[] = { > > > > MODULE_DEVICE_TABLE(i2c, ak8975_id); > > > > +#if defined(CONFIG_ACPI) > > +static int ak8975_detect(struct i2c_client *temp_client, > > + struct i2c_board_info *info) > > +{ > > + struct i2c_adapter *adapter; > > + int i, j; > > + int ret; > > + > > + /* autodetect only when we are behind a mux */ > > + adapter = i2c_parent_is_i2c_adapter(temp_client->adapter); > > + if (!adapter) > > + return -ENODEV; > > + > > + for (i = 0; i < AK_MAX_TYPE; ++i) { > > + ret = ak8975_who_i_am(temp_client, i); > > + if (ret >= 0) { > > + for (j = 0; j < ARRAY_SIZE(ak8975_id) - 1; ++j) { > > + if (i == (int)ak8975_id[j].driver_data) { > > + strlcpy(info->type, ak8975_id[j].name, > > + I2C_NAME_SIZE); > > + return 0; > > + } > > + } > > + } > > + } > > + > > + return -ENODEV; > > +} > > +#endif > > + > > static const struct of_device_id ak8975_of_match[] = { > > { .compatible = "asahi-kasei,ak8975", }, > > { .compatible = "ak8975", }, > > @@ -841,6 +871,11 @@ static struct i2c_driver ak8975_driver = { > > }, > > .probe = ak8975_probe, > > .id_table = ak8975_id, > > +#if defined(CONFIG_ACPI) > > + .class = I2C_CLASS_HWMON, > > + .address_list = I2C_ADDRS(0x0C, 0x0D, 0x0E, 0x0F), > > + .detect = ak8975_detect, > > In contrast to the commit message this is always enabled if the kernel > contains ACPI support, not if the device is a ACPI device. Yes. You don't enable ACPI if you don't need it. It will bring in lots of builtin code if someone did that. > > > +#endif > > }; > > module_i2c_driver(ak8975_driver); > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html