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Fri, 12 Mar 2021 17:17:26 +0100 (CET) Subject: Re: [PATCH] ARM: dts: stm32: Fill GPIO line names on AV96 To: Christoph Niedermaier , "linux-arm-kernel@lists.infradead.org" , "linus.walleij@linaro.org" Cc: Alexandre Torgue , Patrice Chotard , Patrick Delaunay , Maxime Coquelin , "linux-stm32@st-md-mailman.stormreply.com" References: <20200724101610.146403-1-marex@denx.de> <495b2f6b-04b7-c1eb-7aed-cd55636bef46@denx.de> <4530980295044f8ab9c1cfe14e02f90f@dh-electronics.com> From: Marek Vasut Message-ID: <6616e8b0-2b7d-a157-c24f-0493ce03c45b@denx.de> Date: Fri, 12 Mar 2021 17:17:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <4530980295044f8ab9c1cfe14e02f90f@dh-electronics.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210312_161730_339194_ABAD600B X-CRM114-Status: GOOD ( 28.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 3/12/21 4:17 PM, Christoph Niedermaier wrote: > From: Marek Vasut [mailto:marex@denx.de] > Sent: Thursday, August 6, 2020 9:30 AM > >> On 8/6/20 9:09 AM, Christoph Niedermaier wrote: >>> From: Marek Vasut >>> Sent: Friday, July 24, 2020 12:16 PM >>>> >>>> Fill in the custom GPIO line names used by DH. >>>> >>> [...] >>>> +&gpioa { >>>> + gpio-line-names = "", "", "", "", >>>> + "", "", "", "", >>>> + "", "", "", "DH-GPIO-K", >>>> + "DH-GPIO-I", "", "DH-GPIO-A", ""; >>>> +}; >>>> + >>> [...] >>> >>> We have been using the GPIO names at DH electronics for some time and also >>> on other SOMs, but have not yet streamed them. We started with the naming >>> only with a capital letter "A-W" since then without problems. To avoid a >>> hard cut or patching for us and our customers it would be good if we could >>> use the same naming in the mainline kernel as well. Marek, we would be >>> happy if you would adopt our valued GPIO naming in your patch. >> >> My counter-argument to this is that the naming should be unique and >> provide a hint where those GPIO lines come from, so maybe even DH-GPIO-n >> should rather be DHCOM-n . I can't say I'm particularly fond of the >> plain 'n' naming of GPIO lines, because then the GPIO label (and e.g. >> listing in libgpiod tools) does not give any hint what the GPIO is or >> where it comes from. Also, I worry a plain 'n' naming might clash with >> other GPIO IPs easily, while a more unique name can not. > > Hello Marek, > > after an internal discussion, we decided the following: > > Could you update the patch for the Avenger96 to the GPIO naming "AV96-n". > > Moreover for the SOM layer (stm32mp15xx-dhcom-som.dtsi) we would prefer > "DHCOM-n". It would be nice if you could create a patch for it. I don't think we should have any SoM-side gpio-line-names, because once you plug the SoM into new carrier board, the gpio-lane-names will no longer make sense. So, I think all the gpio-line-names should be implemented in the carrier board DTS. As for the naming scheme, I was also hoping Linus might jump in and provide some suggestion on best practice here. I think naming carrier board GPIOs "A", "B", "C",... is too opaque and can easily collide e.g. with GPIO expanders which might be on I2C or so. A naming scheme which encodes the carrier board name is clearer and less likely to cause collision, so "AV96-A", "AV96-B", etc. looks good to me. It is obvious where the GPIO is located and unlikely to collide with any other GPIO name. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel