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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 E7545C433E7 for ; Mon, 31 Aug 2020 16:06:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD6A420767 for ; Mon, 31 Aug 2020 16:06:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728324AbgHaQGx (ORCPT ); Mon, 31 Aug 2020 12:06:53 -0400 Received: from mga11.intel.com ([192.55.52.93]:65335 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727919AbgHaQGx (ORCPT ); Mon, 31 Aug 2020 12:06:53 -0400 IronPort-SDR: FPJk1Gr1IQHRxjxedpw4aP25988Y+OmLBxXSah+k+TzMaK1IxEP9KkxCybCyfr7bTF8EbLwpId GnDW/sZe48pA== X-IronPort-AV: E=McAfee;i="6000,8403,9730"; a="154530118" X-IronPort-AV: E=Sophos;i="5.76,376,1592895600"; d="scan'208";a="154530118" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2020 09:06:52 -0700 IronPort-SDR: 6IY/dpiUSpNNHBjPIMDLOmwwukXVMpmBy7EzW0XaqtS2k+a3zJRGno81ukPA0izBmZihiiYX18 UT99p1pspPGQ== X-IronPort-AV: E=Sophos;i="5.76,376,1592895600"; d="scan'208";a="314398396" Received: from paasikivi.fi.intel.com ([10.237.72.42]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2020 09:06:46 -0700 Received: by paasikivi.fi.intel.com (Postfix, from userid 1000) id 98A0B20623; Mon, 31 Aug 2020 19:06:44 +0300 (EEST) Date: Mon, 31 Aug 2020 19:06:44 +0300 From: Sakari Ailus To: Tomasz Figa Cc: Dongchun Zhu , Mauro Carvalho Chehab , Andy Shevchenko , Rob Herring , Mark Rutland , Nicolas Boichat , Matthias Brugger , Cao Bing Bu , srv_heupstream , "moderated list:ARM/Mediatek SoC support" , "list@263.net:IOMMU DRIVERS , Joerg Roedel ," , Sj Huang , Linux Media Mailing List , linux-devicetree , Louis Kuo , Shengnan Wang =?utf-8?B?KOeOi+Wco+eUtyk=?= , 1095088256@qq.com, matrix.zhu@aliyun.com Subject: Re: [PATCH v13 1/2] media: dt-bindings: media: i2c: Document OV02A10 bindings Message-ID: <20200831160644.GL31019@paasikivi.fi.intel.com> References: <20200710101850.4604-1-dongchun.zhu@mediatek.com> <20200710101850.4604-2-dongchun.zhu@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Tomasz, Thanks for dressing this into words. On Mon, Aug 31, 2020 at 01:44:27PM +0200, Tomasz Figa wrote: > Hi Dongchun, > > On Fri, Jul 10, 2020 at 12:19 PM Dongchun Zhu wrote: > > > > Add YAML device tree binding for OV02A10 CMOS image sensor, > > and the relevant MAINTAINERS entries. > > > > Reviewed-by: Tomasz Figa > > Reviewed-by: Rob Herring > > Signed-off-by: Dongchun Zhu > > --- > > .../bindings/media/i2c/ovti,ov02a10.yaml | 172 +++++++++++++++++++++ > > MAINTAINERS | 7 + > > 2 files changed, 179 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml b/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml > > new file mode 100644 > > index 0000000..3a916cc > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/media/i2c/ovti,ov02a10.yaml > > @@ -0,0 +1,172 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +# Copyright (c) 2020 MediaTek Inc. > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/media/i2c/ovti,ov02a10.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Omnivision OV02A10 CMOS Sensor Device Tree Bindings > > + > > +maintainers: > > + - Dongchun Zhu > > + > > +description: |- > > + The Omnivision OV02A10 is a low-cost, high performance, 1/5-inch, 2 megapixel > > + image sensor, which is the latest production derived from Omnivision's CMOS > > + image sensor technology. Ihis chip supports high frame rate speeds up to 30fps > > + @ 1600x1200 (UXGA) resolution transferred over a 1-lane MIPI interface. The > > + sensor output is available via CSI-2 serial data output. > > + > > +properties: > > + compatible: > > + const: ovti,ov02a10 > > + > > + reg: > > + maxItems: 1 > > + > > + clocks: > > + items: > > + - description: top mux camtg clock > > + - description: divider clock > > + > > + clock-names: > > + items: > > + - const: eclk > > + - const: freq_mux > > Why do we have two clocks here? Looking at the example suggests that > they may be the clocks of the SoC that the integration was done with. > However, the binding must only define the aspects of the particular > device, i.e. this sensor. > > I suppose we should only have "eclk" here and it should be described > as "external clock for the sensor". > > > + > > + clock-frequency: > > + description: > > + Frequency of the eclk clock in Hertz. > > nit: maybe Hz? > > > + > > + dovdd-supply: > > + description: > > + Definition of the regulator used as Digital I/O voltage supply. > > + > > + avdd-supply: > > + description: > > + Definition of the regulator used as Analog voltage supply. > > + > > + dvdd-supply: > > + description: > > + Definition of the regulator used as Digital core voltage supply. > > + > > + powerdown-gpios: > > + description: > > + Must be the device tree identifier of the GPIO connected to the > > + PD_PAD pin. This pin is used to place the OV02A10 into standby mode > > + or shutdown mode. As the line needs to be high for the powerdown mode > > + to be active, it should be marked GPIO_ACTIVE_HIGH. > > + maxItems: 1 > > + > > + reset-gpios: > > + description: > > + Must be the device tree identifier of the GPIO connected to the > > + RST_PD pin. If specified, it will be asserted during driver probe. > > + As the line needs to be low for the reset to be active, it should be > > + marked GPIO_ACTIVE_LOW. > > + maxItems: 1 > > + > > + rotation: > > + description: > > + Definition of the sensor's placement. > > + allOf: > > + - $ref: "/schemas/types.yaml#/definitions/uint32" > > + - enum: > > + - 0 # Sensor Mounted Upright > > + - 180 # Sensor Mounted Upside Down > > + default: 0 > > + > > + ovti,mipi-tx-speed: > > + description: > > + Indication of MIPI transmission speed select, which is to control D-PHY > > + timing setting by adjusting MIPI clock voltage to improve the clock > > + driver capability. > > The description says that the value adjusts "MIPI clock voltage". > Should the property be renamed to "ovti,mipi-clock-voltage"? > > > + allOf: > > + - $ref: "/schemas/types.yaml#/definitions/uint32" > > + - enum: > > + - 0 # 20MHz - 30MHz > > + - 1 # 30MHz - 50MHz > > + - 2 # 50MHz - 75MHz > > + - 3 # 75MHz - 100MHz > > + - 4 # 100MHz - 130MHz > > + default: 3 > > + > > I've discussed this on IRC with Sakari. It sounds like this works as > is for us because the driver currently only supports 1 mode, always > running the link at 390 MHz. This won't scale if one intends to add > more modes, because DT can't be expected to be updated when the driver > changes. The two are expected to be separate and backwards compatible. > > I think we could model this in DT as an array of voltage> pairs. Similarly to the OPP bindings [1]. An example to have > all link speeds up to 390 MHz use the value 4: > > ovti,mipi-clock-voltages = < > /* KHz clock voltage unit */ > 390000 4 > >; > > if one wants to select different voltage for different link, they > could do so as well. With the example below, the driver should > configure "3" for link frequencies <= 150 MHz and "4" for > 150 MHz <= > 390 MHz. Link frequencies > 390 MHz should be disallowed. > > ovti,mipi-clock-voltages = < > /* KHz clock voltage unit */ > 150000 3 > 390000 4 > >; > > What do you think? One more note on my proposal: use the index of the link frequency to access the ovti,mipi-clock-voltages array. That should be more simple for the driver, as the driver is expected to use only link frequencies listed in DT bindings anyway. -- Kind regards, Sakari Ailus