Re: [PATCH v7 1/7] i2c: add I2C Address Translator (ATR) support

[Tomi Valkeinen]

On 19/01/2023 10:21, Luca Ceresoli wrote:

<snip>

> > > > > +void i2c_atr_set_driver_data(struct i2c_atr *atr, void *data)
> > > > > +{
> > > > > +	atr->priv = data;
> > > > > +}
> > > > > +EXPORT_SYMBOL_NS_GPL(i2c_atr_set_driver_data, I2C_ATR);
> > > > > +
> > > > > +void *i2c_atr_get_driver_data(struct i2c_atr *atr)
> > > > > +{
> > > > > +	return atr->priv;
> > > > > +}
> > > > > +EXPORT_SYMBOL_NS_GPL(i2c_atr_get_driver_data, I2C_ATR);
> > > >
> > > > Just to be sure: Is it really _driver_ data and not _device instance_ data?
> > >
> > > It is device instance data indeed. I don't remember why this got
> > > changed, but in v3 it was i2c_atr_set_clientdata().
> >
> > It's me who was and is against calling it clientdata due to possible
> > confusion with i2c_set/get_clientdata() that is about *driver data*.
> > I missed that time the fact that this is about device instance data.
> > I dunno which name would be better in this case, i2c_atr_set/get_client_priv() ?
>
> Not sure I'm following you here. The i2c_atr_set_clientdata() name was
> given for similarity with i2c_set_clientdata(). The latter wraps
> dev_set_drvdata(), which sets `struct device`->driver_data. There is
> one driver_data per each `struct device` instance, not per each driver.
> The same goes for i2c_atr_set_driver_data(): there is one priv pointer
> per each `struct i2c_atr` instance.

I'm a bit confused. What is "driver data" and what is "device instance 
data"?

This deals with the driver's private data, where the "driver" is the 
owner/creator of the i2c-atr. The i2c-atr itself doesn't have a device 
(it's kind of part of the owner's device), and there's no driver in 
i2c-atr.c

I don't like "client" here, as it reminds me of i2c_client (especially 
as we're in i2c context).

What about i2c_atr_set_user_data()? Or "owner_data"?

 Tomi