Messages in this thread | | | Date | Thu, 19 Jan 2023 14:22:26 +0200 | Subject | Re: [PATCH v7 1/7] i2c: add I2C Address Translator (ATR) support | From | Tomi Valkeinen <> |
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On 19/01/2023 13:35, Luca Ceresoli wrote: > Hi Tomi, Andy, > > On Thu, 19 Jan 2023 12:09:57 +0200 > Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> wrote: > >> 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"? > > Ah, only now I got the point Andy made initially about "client" not > being an appropriate word. > > In i2c we have: > > i2c_set_clientdata(struct i2c_client *client, void *data) > ^^^^^^~~~~ ^^^^^^ ~~~~ > > so "client" clearly makes sense there, now here.
Isn't that also used by the i2c_client? A driver which handles an i2c device is the "i2c client", in a sense?
> The same logic applied here would lead to: > > i2c_atr_set_atrdata(struct i2c_atr *atr, void *data) > ^^^~~~~ ^^^ ~~~~ > > which makes sense but it is a ugly IMO.
Here, I think, there's a bit of a difference to the i2c_client case, as we have a separate component for the i2c-atr. Although I guess one can argue that the top level driver is the ATR driver, as it handles the HW, and i2c-atr.c is just a set of helpers, so... I don't know =).
> So I think i2c_atr_get_driver_data() in this v7 makes sense, it's to > set the data that the ATR driver instance needs. > > This is coherent with logic in spi/spi.h: > > spi_set_drvdata(struct spi_device *spi, void *data) > > except for the abbreviation ("_drvdata" vs "_driver_data"). > > Andy, Tomi, would i2c_atr_set_drvdata() be OK for you, just like SPI > does?
Well, I'm good with the current i2c_atr_set_driver_data(). If all agrees that it's "driver data", I'd rather keep it like that. I find this "drvdata" style very odd. Why no underscore between drv and data? Why abbreviate drv, it doesn't really help anything here?
That said, I'm also fine with i2c_atr_set_drvdata if that's the popular opinion (between the three of us, so far ;).
Tomi
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