Messages in this thread | | | Date | Tue, 10 Dec 2013 17:28:04 -0800 | From | Guenter Roeck <> | Subject | Re: [lm-sensors] [PATCH] hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK |
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On 12/10/2013 04:57 PM, José Miguel Gonçalves wrote: > Some I2C bus drivers do not allow zero-lenght data transfers which are
s/lenght/length/
> required to start a mesurement with the HIH6130/1 sensor. Nevertheless,
s/mesurement/measurement/
> we can overcome this limitation by writing a zero dummy byte. This byte > is ignored by the sensor and was verified to be working with the OMAP > I2C bus driver in a BeagleBone board. > > Signed-off-by: José Miguel Gonçalves <jose.goncalves@inov.pt> > --- > drivers/hwmon/hih6130.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwmon/hih6130.c b/drivers/hwmon/hih6130.c > index 2dc37c7..a860cc4 100644 > --- a/drivers/hwmon/hih6130.c > +++ b/drivers/hwmon/hih6130.c > @@ -121,8 +121,20 @@ static int hih6130_update_measurements(struct i2c_client *client) > */ > if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { > > - /* write to slave address, no data, to request a measurement */ > - ret = i2c_master_send(client, tmp, 0); > + /* > + * Write to slave address, to request a measurement.
s/,//
> + * According with the datasheet it should be with no data, but > + * for systems with I2C bus drivers that do not allow zero > + * length packets we write one dummy byte to allow sensor > + * measurements on them. > + */ > + if (i2c_get_functionality(client->adapter) & > + I2C_FUNC_SMBUS_QUICK) { > + ret = i2c_master_send(client, tmp, 0); > + } else { > + tmp[0] = 0; > + ret = i2c_master_send(client, tmp, 1); > + }
You can simplify this code by introducing a variable to hold the write length into struct hih6130. This variable can be initialized with 1 or 0 in the probe function.
if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK)) hih6130->write_length = 0; else hih6130->write_length = 1;
Then replace above code with
tmp[0] = 0; ret = i2c_master_send(client, tmp, hih6130->write_length);
This way you don't have to call i2c_{get,check}_functionality() repeatedly.
Thanks, Guenter > if (ret < 0) > goto out; > >
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