From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH] gpio: palmas: add dt support Date: Tue, 02 Apr 2013 09:30:49 -0600 Message-ID: <515AF9A9.4060407@wwwdotorg.org> References: <1363876214-25933-1-git-send-email-ldewangan@nvidia.com> <5153DC24.7040309@nvidia.com> <515459D8.4010001@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Linus Walleij Cc: Stephen Warren , Laxman Dewangan , "grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org" , "rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On 04/02/2013 03:01 AM, Linus Walleij wrote: > On Thu, Mar 28, 2013 at 3:55 PM, Stephen Warren wrote: >> On 03/27/2013 11:59 PM, Laxman Dewangan wrote: >>> On Wednesday 27 March 2013 06:30 PM, Linus Walleij wrote: >>>> On Thu, Mar 21, 2013 at 3:30 PM, Laxman Dewangan >>>> wrote: >>>> >>>>> +#ifdef CONFIG_OF >>>>> +static struct of_device_id of_palmas_gpio_match[] = { >>>>> + { .compatible = "ti,palmas-gpio"}, >>>>> + { }, >>>>> +}; >>>>> +MODULE_DEVICE_TABLE(of, of_palmas_gpio_match); >>>>> +#endif >>>> >>>> But please drop the #ifdef here unless it causes compile errors >>>> (I don't think it will.) >>>> >>> >>> I am using this table as >>> >>> driver.of_match_table = of_match_ptr(of_palmas_gpio_match), >>> of_match_ptr is macro which is NULL in case of CONFIG_OF not defined. >>> So if I remove ifdefs then it may create build warning as unused variable. >> >> I think Linus's point is that you can simply remove the use of >> of_match_ptr(). The only disadvantage of doing so is that the table will >> always be included in the object file, but it's so small that it's >> probably not worth worrying about. > > Oh I wasn't that smart :-) > > But what you're saying seems true. > > The of_match_ptr() is something > I haven't quite seen before and don't quite understand the > semantics of, why would we use that? Very roughly, of_match_ptr(x) == CONFIG_OF ? x : NULL (although with ifdefs rather than the ternary operator) So, if you have ifdef'd the match table with CONFIG_OF, and reference it from code outside that ifdef, then you need to use of_match_ptr() to reference the table, so it isn't referenced when CONFIG_OF is not defined, and hence never causes link problems. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932627Ab3DBPa4 (ORCPT ); Tue, 2 Apr 2013 11:30:56 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:37479 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761364Ab3DBPay (ORCPT ); Tue, 2 Apr 2013 11:30:54 -0400 Message-ID: <515AF9A9.4060407@wwwdotorg.org> Date: Tue, 02 Apr 2013 09:30:49 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: Linus Walleij CC: Stephen Warren , Laxman Dewangan , "grant.likely@secretlab.ca" , "rob.herring@calxeda.com" , "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" Subject: Re: [PATCH] gpio: palmas: add dt support References: <1363876214-25933-1-git-send-email-ldewangan@nvidia.com> <5153DC24.7040309@nvidia.com> <515459D8.4010001@nvidia.com> In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/02/2013 03:01 AM, Linus Walleij wrote: > On Thu, Mar 28, 2013 at 3:55 PM, Stephen Warren wrote: >> On 03/27/2013 11:59 PM, Laxman Dewangan wrote: >>> On Wednesday 27 March 2013 06:30 PM, Linus Walleij wrote: >>>> On Thu, Mar 21, 2013 at 3:30 PM, Laxman Dewangan >>>> wrote: >>>> >>>>> +#ifdef CONFIG_OF >>>>> +static struct of_device_id of_palmas_gpio_match[] = { >>>>> + { .compatible = "ti,palmas-gpio"}, >>>>> + { }, >>>>> +}; >>>>> +MODULE_DEVICE_TABLE(of, of_palmas_gpio_match); >>>>> +#endif >>>> >>>> But please drop the #ifdef here unless it causes compile errors >>>> (I don't think it will.) >>>> >>> >>> I am using this table as >>> >>> driver.of_match_table = of_match_ptr(of_palmas_gpio_match), >>> of_match_ptr is macro which is NULL in case of CONFIG_OF not defined. >>> So if I remove ifdefs then it may create build warning as unused variable. >> >> I think Linus's point is that you can simply remove the use of >> of_match_ptr(). The only disadvantage of doing so is that the table will >> always be included in the object file, but it's so small that it's >> probably not worth worrying about. > > Oh I wasn't that smart :-) > > But what you're saying seems true. > > The of_match_ptr() is something > I haven't quite seen before and don't quite understand the > semantics of, why would we use that? Very roughly, of_match_ptr(x) == CONFIG_OF ? x : NULL (although with ifdefs rather than the ternary operator) So, if you have ifdef'd the match table with CONFIG_OF, and reference it from code outside that ifdef, then you need to use of_match_ptr() to reference the table, so it isn't referenced when CONFIG_OF is not defined, and hence never causes link problems.