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([2001:9e8:f10a:ad01:ad7e:4d4c:7985:153]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b5cb9e7a23dsm554836166b.23.2025.10.16.08.37.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Oct 2025 08:37:20 -0700 (PDT) Message-ID: <22a84772-0e54-4b99-9bc7-59e7e4633807@gmail.com> Date: Thu, 16 Oct 2025 17:37:20 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 2/2] gpio: add gpio-split driver Content-Language: en-US To: Linus Walleij , Peter Rosin , Geert Uytterhoeven Cc: Bartosz Golaszewski , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20251009223501.570949-1-jelonek.jonas@gmail.com> <20251009223501.570949-3-jelonek.jonas@gmail.com> From: Jonas Jelonek In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Linus, On 14.10.25 10:37, Linus Walleij wrote: > This can be made easier these days, reusing the > forwarder library. I think! Check if I'm right. I think this doesn't really simplify things her. As far as I can see the GPIO forwarder is more targeted toward 1-to-1 scenarios, requiring some (or even more?) "hackery" to fit to my 1-to-many. > This part is maybe the most interesting: > > fwd = devm_gpiochip_fwd_alloc(dev, pctrl->pctrl_data->ngpio); > > Here ngpio will be 1 for your usecase. Giving ngpio=1 here makes the gpiochip only provide a single gpio. This then needs to be the number of GPIOs defined in the DT (number of child nodes). But in this case, the internal 'descs' is allocated accordingly and there's a 1-to-1-mapping between the external offset and internal offset. To solve this I would have to add the same descriptor for the shared gpio multiple times. Not sure if this is a good idea. >> +++ b/drivers/gpio/gpio-split.c > As mentioned I would call this gpio-line-mux.c Sure, will be changed. > Yours, > Linus Walleij Best, Jonas