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Thu, 02 Apr 2020 03:10:11 -0700 (PDT) MIME-Version: 1.0 References: <20200331133346.372517-1-robert.foss@linaro.org> <20200331133346.372517-2-robert.foss@linaro.org> <20200401080705.j4goeqcqhoswhx4u@gilmour.lan> In-Reply-To: <20200401080705.j4goeqcqhoswhx4u@gilmour.lan> From: Robert Foss Date: Thu, 2 Apr 2020 12:10:00 +0200 Message-ID: Subject: Re: [PATCH v6 1/3] media: dt-bindings: ov8856: Document YAML bindings To: Maxime Ripard Cc: Dongchun Zhu , Fabio Estevam , Andy Shevchenko , Sakari Ailus , Tomasz Figa , linux-media , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-kernel , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey Maxime, On Wed, 1 Apr 2020 at 10:07, Maxime Ripard wrote: > > Hi, > > On Tue, Mar 31, 2020 at 03:33:44PM +0200, Robert Foss wrote: > > From: Dongchun Zhu > > > > This patch adds documentation of device tree in YAML schema for the > > OV8856 CMOS image sensor. > > > > Signed-off-by: Dongchun Zhu > > Signed-off-by: Robert Foss > > --- > > > > - Changes since v5: > > * Add assigned-clocks and assigned-clock-rates > > * robher: dt-schema errors > > > > - Changes since v4: > > * Fabio: Change reset-gpio to GPIO_ACTIVE_LOW, explain in description > > * Add clock-lanes property to example > > * robher: Fix syntax error in devicetree example > > > > - Changes since v3: > > * robher: Fix syntax error > > * robher: Removed maxItems > > * Fixes yaml 'make dt-binding-check' errors > > > > - Changes since v2: > > Fixes comments from from Andy, Tomasz, Sakari, Rob. > > * Convert text documentation to YAML schema. > > > > - Changes since v1: > > Fixes comments from Sakari, Tomasz > > * Add clock-frequency and link-frequencies in DT > > > > .../devicetree/bindings/media/i2c/ov8856.yaml | 150 ++++++++++++++++++ > > MAINTAINERS | 1 + > > 2 files changed, 151 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ov8856.yaml b/Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > new file mode 100644 > > index 000000000000..beeddfbb8709 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > @@ -0,0 +1,150 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +# Copyright (c) 2019 MediaTek Inc. > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/media/i2c/ov8856.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Omnivision OV8856 CMOS Sensor Device Tree Bindings > > + > > +maintainers: > > + - Ben Kao > > + - Dongchun Zhu > > + > > +description: |- > > + The Omnivision OV8856 is a high performance, 1/4-inch, 8 megapixel, CMOS > > + image sensor that delivers 3264x2448 at 30fps. It provides full-frame, > > + sub-sampled, and windowed 10-bit MIPI images in various formats via the > > + Serial Camera Control Bus (SCCB) interface. This chip is programmable > > + through I2C and two-wire SCCB. The sensor output is available via CSI-2 > > + serial data output (up to 4-lane). > > + > > +properties: > > + compatible: > > + const: ovti,ov8856 > > + > > + reg: > > + maxItems: 1 > > + > > + clocks: > > + maxItems: 1 > > + > > + clock-names: > > + description: > > + Input clock for the sensor. > > + items: > > + - const: xvclk > > + > > + clock-frequency: > > + description: > > + Frequency of the xvclk clock in Hertz. > > We also had that discussion recently for another omnivision sensor > (ov5645 iirc), but what is clock-frequency useful for? > > It seems that the sensor is passed in clocks, so if you need to > retrieve the clock rate you should use the clock API instead. > > Looking at the driver, it looks like it first retrieves the clock, set > it to clock-frequency, and then checks that this is OV8856_XVCLK_19_2 > (19.2 MHz). As far as I understand it, 19.2MHz is requirement for the sensor mode that currently defaults to. Some modes require higher clock speeds than this however. > > The datasheet says that the sensor can have any frequency in the 6 - > 27 MHz range, so this is a driver limitation and should be set in the > driver using the clock API, and you can always bail out if it doesn't > provide a rate that is not acceptable for the drivers assumption. > > In any case, you don't need clock-frequency here... So your suggestion is that we remove all clocks-rate properties, and replace the clk_get_rate() calls in the driver with clk_set_rate() calls for the desired frequencies? > > > + assigned-clocks: > > + description: > > + Input clock for the sensor. > > + > > + assigned-clock-rates: > > + description: > > + Frequency of the xvclk clock in Hertz. > > And you don't need assigned-clock-rates either. Ack. > > Maxime 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 DE913C43331 for ; Thu, 2 Apr 2020 10:10:19 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AC76B2074D for ; Thu, 2 Apr 2020 10:10:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Nu3bNNg3"; 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MRdlSIlWiqiUEn9v/+BSCM98gAfMn515+Qx9Pso1+1M=; b=Ommcp+H5a0s1TTuo5gBtahsM1hkLtIePbRFuQ1R5PxkbAoIFqgMV4jjrw+jYNTCSLz 3cY4MM/k7zmmQ0A/khv/vnSZ0iIGNai3EHImtafXHex76EEQ5FopKPCqOGuOXf27WcI6 b4GywCin8PXxdDwv6ZyKXrmuOaOWzyqv4dnf2P9jgLvXITYvTyK8TIm29AkdZdmWySBN RLbLo3OBc103BxPm000ewGfaWRNi8WE3GIxJ+YvvMRB6Zx+cNNSAdhdPTvEtjMCYpnSS H8sacyVtknYFn9cQXqPkiDZKIJlVQoH36csHhOapxRY7TGmW1n7Fh+Jv8iiA9n7Mr1s4 1veQ== X-Gm-Message-State: AGi0PuYrLi59VRWyKtDfXitijbTbGq3kqrSXx6gOj/qFrdieetenevsF sw+Kl9EPD8vHIhAN2qRIiDX6J+9ueqe5yw/JuS4xfg== X-Google-Smtp-Source: APiQypKBm/Lg+9lw65OG6XgOJFxflgoP4WFpsTputiWXnE3eeGtQPAOXhxBX+bGTFsX8n8K4MxbqvgyMTSSGZvo3ZmQ= X-Received: by 2002:a9d:6c88:: with SMTP id c8mr1673754otr.272.1585822211618; Thu, 02 Apr 2020 03:10:11 -0700 (PDT) MIME-Version: 1.0 References: <20200331133346.372517-1-robert.foss@linaro.org> <20200331133346.372517-2-robert.foss@linaro.org> <20200401080705.j4goeqcqhoswhx4u@gilmour.lan> In-Reply-To: <20200401080705.j4goeqcqhoswhx4u@gilmour.lan> From: Robert Foss Date: Thu, 2 Apr 2020 12:10:00 +0200 Message-ID: Subject: Re: [PATCH v6 1/3] media: dt-bindings: ov8856: Document YAML bindings To: Maxime Ripard X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200402_031015_584283_BA93AAA7 X-CRM114-Status: GOOD ( 27.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-kernel , Tomasz Figa , Sakari Ailus , Dongchun Zhu , Andy Shevchenko , Fabio Estevam , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" , linux-media Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hey Maxime, On Wed, 1 Apr 2020 at 10:07, Maxime Ripard wrote: > > Hi, > > On Tue, Mar 31, 2020 at 03:33:44PM +0200, Robert Foss wrote: > > From: Dongchun Zhu > > > > This patch adds documentation of device tree in YAML schema for the > > OV8856 CMOS image sensor. > > > > Signed-off-by: Dongchun Zhu > > Signed-off-by: Robert Foss > > --- > > > > - Changes since v5: > > * Add assigned-clocks and assigned-clock-rates > > * robher: dt-schema errors > > > > - Changes since v4: > > * Fabio: Change reset-gpio to GPIO_ACTIVE_LOW, explain in description > > * Add clock-lanes property to example > > * robher: Fix syntax error in devicetree example > > > > - Changes since v3: > > * robher: Fix syntax error > > * robher: Removed maxItems > > * Fixes yaml 'make dt-binding-check' errors > > > > - Changes since v2: > > Fixes comments from from Andy, Tomasz, Sakari, Rob. > > * Convert text documentation to YAML schema. > > > > - Changes since v1: > > Fixes comments from Sakari, Tomasz > > * Add clock-frequency and link-frequencies in DT > > > > .../devicetree/bindings/media/i2c/ov8856.yaml | 150 ++++++++++++++++++ > > MAINTAINERS | 1 + > > 2 files changed, 151 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ov8856.yaml b/Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > new file mode 100644 > > index 000000000000..beeddfbb8709 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > @@ -0,0 +1,150 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +# Copyright (c) 2019 MediaTek Inc. > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/media/i2c/ov8856.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Omnivision OV8856 CMOS Sensor Device Tree Bindings > > + > > +maintainers: > > + - Ben Kao > > + - Dongchun Zhu > > + > > +description: |- > > + The Omnivision OV8856 is a high performance, 1/4-inch, 8 megapixel, CMOS > > + image sensor that delivers 3264x2448 at 30fps. It provides full-frame, > > + sub-sampled, and windowed 10-bit MIPI images in various formats via the > > + Serial Camera Control Bus (SCCB) interface. This chip is programmable > > + through I2C and two-wire SCCB. The sensor output is available via CSI-2 > > + serial data output (up to 4-lane). > > + > > +properties: > > + compatible: > > + const: ovti,ov8856 > > + > > + reg: > > + maxItems: 1 > > + > > + clocks: > > + maxItems: 1 > > + > > + clock-names: > > + description: > > + Input clock for the sensor. > > + items: > > + - const: xvclk > > + > > + clock-frequency: > > + description: > > + Frequency of the xvclk clock in Hertz. > > We also had that discussion recently for another omnivision sensor > (ov5645 iirc), but what is clock-frequency useful for? > > It seems that the sensor is passed in clocks, so if you need to > retrieve the clock rate you should use the clock API instead. > > Looking at the driver, it looks like it first retrieves the clock, set > it to clock-frequency, and then checks that this is OV8856_XVCLK_19_2 > (19.2 MHz). As far as I understand it, 19.2MHz is requirement for the sensor mode that currently defaults to. Some modes require higher clock speeds than this however. > > The datasheet says that the sensor can have any frequency in the 6 - > 27 MHz range, so this is a driver limitation and should be set in the > driver using the clock API, and you can always bail out if it doesn't > provide a rate that is not acceptable for the drivers assumption. > > In any case, you don't need clock-frequency here... So your suggestion is that we remove all clocks-rate properties, and replace the clk_get_rate() calls in the driver with clk_set_rate() calls for the desired frequencies? > > > + assigned-clocks: > > + description: > > + Input clock for the sensor. > > + > > + assigned-clock-rates: > > + description: > > + Frequency of the xvclk clock in Hertz. > > And you don't need assigned-clock-rates either. Ack. > > Maxime _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel