On Wed, Aug 3, 2016 at 8:33 PM, Alison Schofield <amsfield22@xxxxxxxxx> wrote:
> Replace the i2c_smbus_read_byte commmands used to retrieve the sensor
> data with an i2c_master_recv command.
>
> The smbus read byte method fails because the device does not expect a
> stop condition after sending the first byte. When we issue the second
> read, we are getting the first byte again. Net effect is that of the 14
> bits used for the measurement, the 8 most significant bits are correct,
> the lower 6 are not.
>
> None of the smbus read protocols follow the pattern this device requires
> (S Addr Rd [A] Data [A] Data NA P), hence the switch to an i2c receive
> transaction.
>
> Signed-off-by: Alison Schofield <amsfield22@xxxxxxxxx>
> Cc: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> ---
> drivers/iio/humidity/hdc100x.c | 27 +++++++--------------------
> 1 file changed, 7 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c
> index a03832a..643a42d 100644
> --- a/drivers/iio/humidity/hdc100x.c
> +++ b/drivers/iio/humidity/hdc100x.c
> @@ -142,7 +142,7 @@ static int hdc100x_get_measurement(struct hdc100x_data *data,
> struct i2c_client *client = data->client;
> int delay = data->adc_int_us[chan->address];
> int ret;
> - int val;
> + u8 buf[2];
>
> /* start measurement */
> ret = i2c_smbus_write_byte(client, chan->address);
> @@ -154,26 +154,13 @@ static int hdc100x_get_measurement(struct hdc100x_data *data,
> /* wait for integration time to pass */
> usleep_range(delay, delay + 1000);
>
> - /*
> - * i2c_smbus_read_word_data cannot() be used here due to the command
> - * value not being understood and causes NAKs preventing any reading
> - * from being accessed.
> - */
> - ret = i2c_smbus_read_byte(client);
> + /* read the 2 byte measurement */
> + ret = i2c_master_recv(data->client, buf, 2);
> if (ret < 0) {
> - dev_err(&client->dev, "cannot read high byte measurement");
> + dev_err(&client->dev, "cannot read sensor data\n");
> return ret;
> }
> - val = ret << 8;
> -
> - ret = i2c_smbus_read_byte(client);
> - if (ret < 0) {
> - dev_err(&client->dev, "cannot read low byte measurement");
> - return ret;
> - }
> - val |= ret;
> -
> - return val;
> + return (int)(buf[0] << 8 | buf[1]);
Pretty sure you don't need to cast to int type here.
> }
>
> static int hdc100x_get_heater_status(struct hdc100x_data *data)
> @@ -272,8 +259,8 @@ static int hdc100x_probe(struct i2c_client *client,
> struct iio_dev *indio_dev;
> struct hdc100x_data *data;
>
> - if (!i2c_check_functionality(client->adapter,
> - I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))
> + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
> + I2C_FUNC_SMBUS_BYTE | I2C_FUNC_I2C))
Not sure we want to kill smbus support for this device... iwe should
have two read methods for i2c and smbus (see the PulsedLight LIDAR
driver) in this case.
Ideally I wouldn't have written it with only smbus in mind, but can
kill backwards compatibility unless we have a good reason.
Thanks,
Matt
> return -EOPNOTSUPP;
>
> indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> --
> 2.1.4
>
--
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
