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Tue, 21 Oct 2025 05:22:58 -0700 (PDT) MIME-Version: 1.0 References: <20250924-gpio-shared-v1-0-775e7efeb1a3@linaro.org> In-Reply-To: From: Bartosz Golaszewski Date: Tue, 21 Oct 2025 14:22:46 +0200 X-Gm-Features: AS18NWBF0GY_y5H5_yrBjx5aMTjq-BCBKISyHH-S44AO8cdbNH0Bf9m_yOfn5F8 Message-ID: Subject: Re: [PATCH RFC 0/9] gpio: improve support for shared GPIOs To: Manivannan Sadhasivam Cc: Dmitry Torokhov , Kees Cook , Mika Westerberg , Andrew Morton , Linus Walleij , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Saravana Kannan , Greg Kroah-Hartman , Andy Shevchenko , Catalin Marinas , Will Deacon , Srinivas Kandagatla , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sound@vger.kernel.org, linux-arm-msm@vger.kernel.org, Bartosz Golaszewski Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251021_052300_861109_BF634D2C X-CRM114-Status: GOOD ( 18.47 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 21, 2025 at 2:20=E2=80=AFPM Manivannan Sadhasivam wrote: > > > > > And with the implementation this series proposes it would mean that > > the perst signal will go high after the first endpoint pwrctl driver > > sets it to high and only go down once the last driver sets it to low. > > The only thing I'm not sure about is the synchronization between the > > endpoints - how do we wait for all of them to be powered-up before > > calling the last gpiod_set_value()? > > > > That will be handled by the pwrctrl core. Not today, but in the coming da= ys. > But is this the right approach or are you doing it this way *because* there's no support for enable-counted GPIOs as of yet? Bart