From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4496014B965; Sat, 22 Jun 2024 14:23:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719066208; cv=none; b=apWiESOn4JdBDVYvpGNolEJQL+hjWunn3NGD0Qn5K3JBKKt78T6Pya5Bc0PNaHPlW/IMaKkNAvzVkFx/eEfLE3p/sCkRHuqEcT+4i2xfMauzcHfW74bqDeyxURDwQAmxKqT25IAEIlgQ+1Nd2AWEaLWlKeKafxLWOwkTO9JG5b8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719066208; c=relaxed/simple; bh=HuCIOk+h3mK4PW2KP2sXGEDMU9RhK58+RDYWMFu2e4c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NeozpG1AndTChQgNdyJp4LH3noNqkLYlelZEpgzX8pqSVx73Iuw+cA3M9+dpoIx6BiQMbvRfuHaqbLdkjxi9H+9bsTh9UmWQMBPWGMrW13fm9IUny7DRFj31RwDoQ6pCN6+iOq1q7ihNgMa4ZTL5MR7BZFk1G6oFc1ZXgleenz0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JKOwHnBj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JKOwHnBj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7248DC3277B; Sat, 22 Jun 2024 14:23:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719066207; bh=HuCIOk+h3mK4PW2KP2sXGEDMU9RhK58+RDYWMFu2e4c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JKOwHnBj8RmBKx6o3qG8meGqotnHnZo04ik0Gv1/7iWwpqLTDySE7oTqC1DLB1vlr L2Qoy9Rk0acWGGuCPPztZZM2xNGAJh9634G0DJn9M31fXaWkHjDNwenCEEZdGOHJF5 bOs1X1ZFYipFiJ0nBTh5wCGufZy+1d+sz6kFwJIJPuZWN+kYXMh+rmDC0GoNyrhe5X MpxUA9BIRrtaTLFb4ms+W7c2ldlQ/xluYUWGAHbGk7oO4TnI6I5WeOmcN0Tonomwsb BtkonSc9IXyNTu6aGmvXKud7XaYxmKRqnrHYDk1JInCNuDHoAgZ6sqHTMnuZRcZZ4J knHkxM4NNqL2g== Received: by pali.im (Postfix) id 77536BF5; Sat, 22 Jun 2024 16:23:24 +0200 (CEST) Date: Sat, 22 Jun 2024 16:23:24 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Hans de Goede Cc: Ilpo =?utf-8?B?SsOkcnZpbmVu?= , Andy Shevchenko , Paul Menzel , Wolfram Sang , eric.piel@tremplin-utc.net, Marius Hoch , Dell.Client.Kernel@dell.com, Kai Heng Feng , platform-driver-x86@vger.kernel.org, Jean Delvare , Andi Shyti , linux-i2c@vger.kernel.org Subject: Re: [PATCH v3 2/6] i2c: i801: Use a different adapter-name for IDF adapters Message-ID: <20240622142324.eocv3iv2tkxeig2c@pali> References: <20240621122503.10034-1-hdegoede@redhat.com> <20240621122503.10034-3-hdegoede@redhat.com> <20240622124644.hndwwp44sfbiiq7o@pali> <8c45cc19-2164-46ea-a388-de23885c3323@redhat.com> <20240622140840.n5733l4ere26gnra@pali> <9736d178-ae8b-4e70-9b9f-7933d285f74c@redhat.com> Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9736d178-ae8b-4e70-9b9f-7933d285f74c@redhat.com> User-Agent: NeoMutt/20180716 On Saturday 22 June 2024 16:14:11 Hans de Goede wrote: > Hi Pali, > > On 6/22/24 4:08 PM, Pali Rohár wrote: > > On Saturday 22 June 2024 15:56:03 Hans de Goede wrote: > >> Hi, > >> > >> On 6/22/24 2:46 PM, Pali Rohár wrote: > >>> On Friday 21 June 2024 14:24:57 Hans de Goede wrote: > >>>> On chipsets with a second 'Integrated Device Function' SMBus controller use > >>>> a different adapter-name for the second IDF adapter. > >>>> > >>>> This allows platform glue code which is looking for the primary i801 > >>>> adapter to manually instantiate i2c_clients on to differentiate > >>>> between the 2. > >>>> > >>>> This allows such code to find the primary i801 adapter by name, without > >>>> needing to duplicate the PCI-ids to feature-flags mapping from i2c-i801.c. > >>>> > >>>> Signed-off-by: Hans de Goede > >>>> --- > >>>> drivers/i2c/busses/i2c-i801.c | 9 +++++++-- > >>>> 1 file changed, 7 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c > >>>> index d2d2a6dbe29f..5ac5bbd60d45 100644 > >>>> --- a/drivers/i2c/busses/i2c-i801.c > >>>> +++ b/drivers/i2c/busses/i2c-i801.c > >>>> @@ -1760,8 +1760,13 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id) > >>>> > >>>> i801_add_tco(priv); > >>>> > >>>> - snprintf(priv->adapter.name, sizeof(priv->adapter.name), > >>>> - "SMBus I801 adapter at %04lx", priv->smba); > >>>> + if (priv->features & FEATURE_IDF) > >>>> + snprintf(priv->adapter.name, sizeof(priv->adapter.name), > >>>> + "SMBus I801 IDF adapter at %04lx", priv->smba); > >>>> + else > >>>> + snprintf(priv->adapter.name, sizeof(priv->adapter.name), > >>>> + "SMBus I801 adapter at %04lx", priv->smba); > >>>> + > >>> > >>> User visible name is identifier for user / human. > >>> > >>> If somebody is going to read this code in next 10 years then can ask > >>> question why to have different name for IDF FEATURE and not also for > >>> other features? And can come to conclusion to unify all names to be > >>> same (why not? it is user identifier). > >> > >> That is a good point, I'll add a comment about this for the next > >> version. > >> > >>> Depending on user names between different kernel subsystem is fragile, > >>> specially for future as rename can happen. > >> > >> Relying no devices names to find devices is standard practice. E.g. > >> this is how 99% of the platform drivers bind to platform devices > >> by the driver and the device having the same name. > > > > But here it is adapter name which is more likely description, not the > > device name which is used for binding. > > It is still matching on a name. > > >>> If you are depending on FEATURE_IDF flag then check for the flag > >>> directly, and not hiding the flag by serializing it into the user > >>> visible name (char[] variable) and then de-serializing it in different > >>> kernel subsystem. If the flag is not exported yet then export it via > >>> some function or other API. > >> > >> Exporting this through some new function is non trivial and adds > >> extra dependencies between modules, causing issues when one is builtin > >> and the other is build as a module. > > > > Access to "struct i801_priv *" is not possible? For example via > > dev_get_drvdata() on "struct device *" which you have in > > smo8800_find_i801()? > > > > Because if it is possible then you can create an inline function in some > > shared header file which access this flag. Not perfect (as accessing > > private data is not the best thing) but can avoid dependences between > > modules. > > Prodding inside another drivers private driver struct is a big nono > and much much more fragile then the name checking. I know, that is why I wrote to access this structure and flags in separate function which can be an inline in e.g. i2c-i801.h header file. > Regards, > > Hans > >