From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v11 2/8] mfd: bd70528: Support ROHM bd70528 PMIC - core Date: Thu, 4 Apr 2019 09:21:53 +0100 Message-ID: <20190404082153.GP6830@dell> References: <20190403093015.GJ11301@dell> <20190403101003.GC3493@localhost.localdomain> <20190403112559.GP11301@dell> <85b20828bb4fb51e6df1d5d9d1c1f667db3a7c48.camel@fi.rohmeurope.com> <20190404025234.GB6830@dell> <6775a75d1ee3ab96123d84b077881beedc358d12.camel@fi.rohmeurope.com> <20190404065452.GD6830@dell> <20190404072449.GE3493@localhost.localdomain> <20190404075640.GV22216@piout.net> <70a8a87a403eb2ab8f0aad2a26456de8a162f363.camel@fi.rohmeurope.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <70a8a87a403eb2ab8f0aad2a26456de8a162f363.camel@fi.rohmeurope.com> Sender: linux-kernel-owner@vger.kernel.org To: "Vaittinen, Matti" Cc: "alexandre.belloni@bootlin.com" , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , "mazziesaccount@gmail.com" , "mturquette@baylibre.com" , "devicetree@vger.kernel.org" , "linux-pm@vger.kernel.org" , "sre@kernel.org" , "linus.walleij@linaro.org" , "sboyd@kernel.org" , "linux-gpio@vger.kernel.org" , "broonie@kernel.org" , "Mutanen, Mikko" , "a.zummo@towertech.it" , "mark.rutland@arm.com" linux List-Id: linux-gpio@vger.kernel.org On Thu, 04 Apr 2019, Vaittinen, Matti wrote: > Hello Alexandre, > > On Thu, 2019-04-04 at 09:56 +0200, Alexandre Belloni wrote: > > On 04/04/2019 10:24:49+0300, Matti Vaittinen wrote: > > > On Thu, Apr 04, 2019 at 07:54:52AM +0100, Lee Jones wrote: > > > > On Thu, 04 Apr 2019, Vaittinen, Matti wrote: > > > > > > > > > Actually, now that I thik of it the right way to do this would > > > > > have > > > > > been the function pointer in parent data as was done in > > > > > original patch > > > > > set. HW-colleagues tend to re-use HW blocks, and we like to re- > > > > > use our > > > > > drivers. If the next PMIC from ROHM uses same RTC block but > > > > > does not > > > > > provide watchdog - then it is cleanest solution to fall back to > > > > > function pointer and leave it to NULL when there is no WDT or > > > > > when WDT > > > > > is unused. Another option is to export dummy function - which > > > > > is not so > > > > > nice. > > > > > > > > I think the converse is true. > > > > > > > > Pointers to functions outside of a subsystem API context are > > > > generally > > > > horrible. It's much nicer to call a function which can be easily > > > > stubbed out in a header file based on a Kconfig option. It's how > > > > most > > > > kernel APIs work. > > > > > > I hate to admit but I see your point. This nicely solves any issues > > > in > > > syncronizing the startup for driver providing function pointer and > > > for > > > driver using it. > > > > > > > Wouldn't it be easier to register the watchdog driver as part of the > > RTC > > driver? > > > > As I see it, the wdt is just a glorified RTC alarm. > > Do you suggest me to put all the stuff now placed in > drivers/watchdog/bd70528_wdt.c into rtc driver? It would be doable - > but I'd rather kept the WDT independent module so that it can be left > out of config if WDT needs not to be used. And same with RTC. Also, re- > use of RTC driver in HW which does not include WDT is easier when WDT > is a separate module. To me it looks much cleaner to have the WDT as > own module than polluting the RTC driver with config ifdefs. I haven't looked at the code, but I agree with this in principle. I'm a firm believer of having functionality in the most appropriate subsystem. IMHO, if a device can be neatly split 9/10 it should be. > But from HW perspective you are correct. The WDT in BD70528 seems to be > kind of RTC alarm which shuts of the PMIC if triggered. > > Br, > Matti Vaittinen -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog 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 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EEB5DC4360F for ; Thu, 4 Apr 2019 08:22:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BA8A72075E for ; Thu, 4 Apr 2019 08:22:07 +0000 (UTC) Authentication-Results: mail.kernel.org; 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Thu, 04 Apr 2019 01:22:03 -0700 (PDT) Date: Thu, 4 Apr 2019 09:21:53 +0100 From: Lee Jones To: "Vaittinen, Matti" Cc: "alexandre.belloni@bootlin.com" , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , "mazziesaccount@gmail.com" , "mturquette@baylibre.com" , "devicetree@vger.kernel.org" , "linux-pm@vger.kernel.org" , "sre@kernel.org" , "linus.walleij@linaro.org" , "sboyd@kernel.org" , "linux-gpio@vger.kernel.org" , "broonie@kernel.org" , "Mutanen, Mikko" , "a.zummo@towertech.it" , "mark.rutland@arm.com" , "linux@roeck-us.net" , "linux-watchdog@vger.kernel.org" , "lgirdwood@gmail.com" , "bgolaszewski@baylibre.com" , "wim@linux-watchdog.org" , "linux-clk@vger.kernel.org" , "linux-rtc@vger.kernel.org" , "Haikola, Heikki" Subject: Re: [PATCH v11 2/8] mfd: bd70528: Support ROHM bd70528 PMIC - core Message-ID: <20190404082153.GP6830@dell> References: <20190403093015.GJ11301@dell> <20190403101003.GC3493@localhost.localdomain> <20190403112559.GP11301@dell> <85b20828bb4fb51e6df1d5d9d1c1f667db3a7c48.camel@fi.rohmeurope.com> <20190404025234.GB6830@dell> <6775a75d1ee3ab96123d84b077881beedc358d12.camel@fi.rohmeurope.com> <20190404065452.GD6830@dell> <20190404072449.GE3493@localhost.localdomain> <20190404075640.GV22216@piout.net> <70a8a87a403eb2ab8f0aad2a26456de8a162f363.camel@fi.rohmeurope.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <70a8a87a403eb2ab8f0aad2a26456de8a162f363.camel@fi.rohmeurope.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 04 Apr 2019, Vaittinen, Matti wrote: > Hello Alexandre, > > On Thu, 2019-04-04 at 09:56 +0200, Alexandre Belloni wrote: > > On 04/04/2019 10:24:49+0300, Matti Vaittinen wrote: > > > On Thu, Apr 04, 2019 at 07:54:52AM +0100, Lee Jones wrote: > > > > On Thu, 04 Apr 2019, Vaittinen, Matti wrote: > > > > > > > > > Actually, now that I thik of it the right way to do this would > > > > > have > > > > > been the function pointer in parent data as was done in > > > > > original patch > > > > > set. HW-colleagues tend to re-use HW blocks, and we like to re- > > > > > use our > > > > > drivers. If the next PMIC from ROHM uses same RTC block but > > > > > does not > > > > > provide watchdog - then it is cleanest solution to fall back to > > > > > function pointer and leave it to NULL when there is no WDT or > > > > > when WDT > > > > > is unused. Another option is to export dummy function - which > > > > > is not so > > > > > nice. > > > > > > > > I think the converse is true. > > > > > > > > Pointers to functions outside of a subsystem API context are > > > > generally > > > > horrible. It's much nicer to call a function which can be easily > > > > stubbed out in a header file based on a Kconfig option. It's how > > > > most > > > > kernel APIs work. > > > > > > I hate to admit but I see your point. This nicely solves any issues > > > in > > > syncronizing the startup for driver providing function pointer and > > > for > > > driver using it. > > > > > > > Wouldn't it be easier to register the watchdog driver as part of the > > RTC > > driver? > > > > As I see it, the wdt is just a glorified RTC alarm. > > Do you suggest me to put all the stuff now placed in > drivers/watchdog/bd70528_wdt.c into rtc driver? It would be doable - > but I'd rather kept the WDT independent module so that it can be left > out of config if WDT needs not to be used. And same with RTC. Also, re- > use of RTC driver in HW which does not include WDT is easier when WDT > is a separate module. To me it looks much cleaner to have the WDT as > own module than polluting the RTC driver with config ifdefs. I haven't looked at the code, but I agree with this in principle. I'm a firm believer of having functionality in the most appropriate subsystem. IMHO, if a device can be neatly split 9/10 it should be. > But from HW perspective you are correct. The WDT in BD70528 seems to be > kind of RTC alarm which shuts of the PMIC if triggered. > > Br, > Matti Vaittinen -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog