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Sat, 02 Nov 2024 07:31:58 -0700 (PDT) Received: from eichest-laptop ([2a02:168:af72:0:492c:2677:72f4:9f57]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-381c1189118sm8196240f8f.116.2024.11.02.07.31.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 Nov 2024 07:31:58 -0700 (PDT) Date: Sat, 2 Nov 2024 15:31:56 +0100 From: Stefan Eichenberger To: Shawn Guo Cc: robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, francesco.dolcini@toradex.com, devicetree@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Stefan Eichenberger Subject: Re: [PATCH v1 1/2] arm64: dts: imx8mm-verdin: add single-master property to all i2c nodes Message-ID: References: <20241025095915.22313-1-eichest@gmail.com> <20241025095915.22313-2-eichest@gmail.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Shawn, On Sat, Nov 02, 2024 at 12:52:08PM +0800, Shawn Guo wrote: > On Fri, Oct 25, 2024 at 11:58:02AM +0200, Stefan Eichenberger wrote: > > From: Stefan Eichenberger > > > > By default we expect all i2c nodes to be single-master, we do not have > > any module or carrier board that uses multi-master mode on any i2c > > controller. With this property set, we benefit from optimisations made > > exclusively for single-masters. > > > > Signed-off-by: Stefan Eichenberger > > --- > > arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi > > index 5fa3959141911..95d5d2333ca1e 100644 > > --- a/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi > > +++ b/arch/arm64/boot/dts/freescale/imx8mm-verdin.dtsi > > @@ -367,6 +367,7 @@ &i2c1 { > > pinctrl-1 = <&pinctrl_i2c1_gpio>; > > scl-gpios = <&gpio5 14 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>; > > sda-gpios = <&gpio5 15 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>; > > + single-master; > > Hmm, I do not see this property is documented in i2c-imx bindings. According to the discussion we had in this thread https://lore.kernel.org/linux-i2c/2bbddaxyjkxfmlgmq3yqcbzo7dsb2pq5bvdatk2y4ig4iintkt@35btqkdv7sy3/ it is not necessary to have the property documentation in the i2c-imx binding because it is already documented in the dt-schema: https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/i2c/i2c-controller.yaml In the initial discussion, it was addressed for multi-master setups, but it also applies for single-master. See also this discussion: https://lore.kernel.org/all/bcdd6cae28edd9dd05a71118f9979e7460688775.camel@pengutronix.de/ Let me know if I have missed anything or misunderstood. Regards, Stefan