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 E16B0C00A5A for ; Thu, 19 Jan 2023 13:02:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230319AbjASNB7 (ORCPT ); Thu, 19 Jan 2023 08:01:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230487AbjASNBT (ORCPT ); Thu, 19 Jan 2023 08:01:19 -0500 Received: from relay6-d.mail.gandi.net (relay6-d.mail.gandi.net [217.70.183.198]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C579337565; Thu, 19 Jan 2023 05:01:03 -0800 (PST) Received: from booty (unknown [77.244.183.192]) (Authenticated sender: luca.ceresoli@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 84417C0002; Thu, 19 Jan 2023 13:00:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1674133262; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZtBO/H//7lVetyBYfz8PbXrkUfECY93kbBBF1YE8iqk=; b=Po1eYWeD5DbyoV+Oqs67NNBLcNdUJrDdEIsG/I998h/ez1bpX6XdQ08LGtSp6dq4eTT+7g tgjv6Y8n9eQPTPQUD+JwaGhkVFwPNSVUAvKfNuAI0uMcg5yUljnxiapb+G8zS73/7ik4C2 oI4nxAXcR7+tU21zv1YPhypPvrUXjCnF9hR7SZAYB97/m6IJeMXwov5nhAA2DFg7aY39N+ 6JGsL4Oj8MlU4/BoBgE1i8pKD1xacaKKETsPSdCsiSgxOPY/YBTtn4K6+Pc4mJa4JLKtvW 9TaKxUgx4aMpS+NP2O0Id7h02c/zsZYBzWB6e13COvJ3eHoc/LAHTMlPAXj9lw== Date: Thu, 19 Jan 2023 14:00:56 +0100 From: Luca Ceresoli To: Tomi Valkeinen 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 , Krzysztof =?UTF-8?Q?Ha=C5=82asa?= , Marek Vasut , Luca Ceresoli Subject: Re: [PATCH v7 1/7] i2c: add I2C Address Translator (ATR) support Message-ID: <20230119140056.686c0dea@booty> In-Reply-To: <79331f60-0849-9d5a-822a-987df01a4b96@ideasonboard.com> References: <20230118124031.788940-1-tomi.valkeinen@ideasonboard.com> <20230118124031.788940-2-tomi.valkeinen@ideasonboard.com> <20230118181753.7a325953@booty> <20230119092115.02cbbab3@booty> <20230119123520.7f1aa680@booty> <79331f60-0849-9d5a-822a-987df01a4b96@ideasonboard.com> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tomi, Andy, On Thu, 19 Jan 2023 14:22:26 +0200 Tomi Valkeinen wrote: > 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? Agreed, I'm OK with either form of "driver data". -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com