From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BEADC46467 for ; Thu, 19 Jan 2023 12:23:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229834AbjASMXC (ORCPT ); Thu, 19 Jan 2023 07:23:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229974AbjASMWm (ORCPT ); Thu, 19 Jan 2023 07:22:42 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1558078A81; Thu, 19 Jan 2023 04:22:32 -0800 (PST) Received: from [192.168.1.15] (91-154-32-225.elisa-laajakaista.fi [91.154.32.225]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id B8BCB501; Thu, 19 Jan 2023 13:22:28 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1674130949; bh=HKd24MpJPUA2cBn9+Zxn633AqY8BeWf29Z3k0lXodMQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Gns5S8qh8jwvaj99tc5g1AfeyxIAkIZjBq/9Tf4k7lIvj53bCAPsZzS7pmRhgSV/K Kd29mhjrhapWvLrf+ZBu5OqoPbOGZiDbottCGG0ijhc4lJ5D6cdU2WXbKaac7PfUkw ars7HGmzXuEqzQakKo+WnqS61YcZJLewaaQELaI4= Message-ID: <79331f60-0849-9d5a-822a-987df01a4b96@ideasonboard.com> Date: Thu, 19 Jan 2023 14:22:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH v7 1/7] i2c: add I2C Address Translator (ATR) support Content-Language: en-US To: Luca Ceresoli Cc: Andy Shevchenko , linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Wolfram Sang , Matti Vaittinen , Laurent Pinchart , Mauro Carvalho Chehab , Peter Rosin , Liam Girdwood , Mark Brown , Sakari Ailus , Michael Tretter , Shawn Tu , Hans Verkuil , Mike Pagano , =?UTF-8?Q?Krzysztof_Ha=c5=82asa?= , Marek Vasut , Luca Ceresoli References: <20230118124031.788940-1-tomi.valkeinen@ideasonboard.com> <20230118124031.788940-2-tomi.valkeinen@ideasonboard.com> <20230118181753.7a325953@booty> <20230119092115.02cbbab3@booty> <20230119123520.7f1aa680@booty> From: Tomi Valkeinen In-Reply-To: <20230119123520.7f1aa680@booty> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 19/01/2023 13:35, Luca Ceresoli wrote: > Hi Tomi, Andy, > > On Thu, 19 Jan 2023 12:09:57 +0200 > Tomi Valkeinen wrote: > >> On 19/01/2023 10:21, Luca Ceresoli wrote: >> >> >> >>>>>>> +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