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Date:   Thu, 19 Jan 2023 12:09:57 +0200
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Subject: Re: [PATCH v7 1/7] i2c: add I2C Address Translator (ATR) support
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To:     Luca Ceresoli <luca.ceresoli@bootlin.com>,
        Andy Shevchenko <andriy.shevchenko@intel.com>
Cc:     linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Wolfram Sang <wsa@kernel.org>,
        Matti Vaittinen <Matti.Vaittinen@fi.rohmeurope.com>,
        Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Peter Rosin <peda@axentia.se>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Michael Tretter <m.tretter@pengutronix.de>,
        Shawn Tu <shawnx.tu@intel.com>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Mike Pagano <mpagano@gentoo.org>,
        =?UTF-8?Q?Krzysztof_Ha=c5=82asa?= <khalasa@piap.pl>,
        Marek Vasut <marex@denx.de>,
        Luca Ceresoli <luca@lucaceresoli.net>
References: <20230118124031.788940-1-tomi.valkeinen@ideasonboard.com>
 <20230118124031.788940-2-tomi.valkeinen@ideasonboard.com>
 <Y8gA+cz9m7PaEhfP@smile.fi.intel.com> <20230118181753.7a325953@booty>
 <Y8gu4mlXUlyiFKZD@smile.fi.intel.com> <20230119092115.02cbbab3@booty>
From:   Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
In-Reply-To: <20230119092115.02cbbab3@booty>
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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