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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 22712CA9ED3 for ; Mon, 4 Nov 2019 19:02:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2CA120848 for ; Mon, 4 Nov 2019 19:02:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="tBXMnl5G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728849AbfKDTCM (ORCPT ); Mon, 4 Nov 2019 14:02:12 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:57980 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727998AbfKDTCL (ORCPT ); Mon, 4 Nov 2019 14:02:11 -0500 Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 2257752C; Mon, 4 Nov 2019 20:02:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1572894129; bh=kvR1ciF/jrbAVq1q5F7pP9qO8GkfA6eHj67avqWv0NA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tBXMnl5Gr+CbG5Gux5GYBO40MA0CKG6md1kU/uj7NCZB9A8mD5/3WF2OQDT1e5RKB I2/ea+yCwoMy/5l6CO9/Qu5HWEYAPtbikz3JnWq9Jahru6r/zuc8gc9qWVozpr9Jq6 ThFIZuX3jjf7Ut32TdgwLts4//hgObWR1BDwvYhs= Date: Mon, 4 Nov 2019 21:02:01 +0200 From: Laurent Pinchart To: Sakari Ailus Cc: Manivannan Sadhasivam , mchehab@kernel.org, robh+dt@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, c.barrett@framos.com, a.brela@framos.com, peter.griffin@linaro.org Subject: Re: [PATCH v4 1/2] dt-bindings: media: i2c: Add IMX296 CMOS sensor binding Message-ID: <20191104190201.GF4913@pendragon.ideasonboard.com> References: <20191030094902.32582-1-manivannan.sadhasivam@linaro.org> <20191030094902.32582-2-manivannan.sadhasivam@linaro.org> <20191031131538.GA9170@pendragon.ideasonboard.com> <20191031134512.GB24273@mani> <20191031141141.GD5018@pendragon.ideasonboard.com> <20191031142817.GK6253@valkosipuli.retiisi.org.uk> <20191031165444.GE5018@pendragon.ideasonboard.com> <20191031170837.GN6253@valkosipuli.retiisi.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20191031170837.GN6253@valkosipuli.retiisi.org.uk> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sakari, On Thu, Oct 31, 2019 at 07:08:37PM +0200, Sakari Ailus wrote: > On Thu, Oct 31, 2019 at 06:54:44PM +0200, Laurent Pinchart wrote: > > On Thu, Oct 31, 2019 at 04:28:17PM +0200, Sakari Ailus wrote: > >> On Thu, Oct 31, 2019 at 04:11:41PM +0200, Laurent Pinchart wrote: > >>> On Thu, Oct 31, 2019 at 07:15:12PM +0530, Manivannan Sadhasivam wrote: > >>>> On Thu, Oct 31, 2019 at 03:15:38PM +0200, Laurent Pinchart wrote: > >>>>> On Wed, Oct 30, 2019 at 03:19:01PM +0530, Manivannan Sadhasivam wrote: > >>>>>> Add YAML devicetree binding for IMX296 CMOS image sensor. Let's also > >>>>>> add MAINTAINERS entry for the binding and driver. > >>>>>> > >>>>>> Signed-off-by: Manivannan Sadhasivam > >>>>>> --- > >>>>>> .../devicetree/bindings/media/i2c/imx296.yaml | 94 +++++++++++++++++++ > >>>>>> MAINTAINERS | 8 ++ > >>>>>> 2 files changed, 102 insertions(+) > >>>>>> create mode 100644 Documentation/devicetree/bindings/media/i2c/imx296.yaml > >>>>>> > >>>>>> diff --git a/Documentation/devicetree/bindings/media/i2c/imx296.yaml b/Documentation/devicetree/bindings/media/i2c/imx296.yaml > >>>>>> new file mode 100644 > >>>>>> index 000000000000..c04ec2203268 > >>>>>> --- /dev/null > >>>>>> +++ b/Documentation/devicetree/bindings/media/i2c/imx296.yaml > >>>>>> @@ -0,0 +1,94 @@ > >>>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > >>>>>> +%YAML 1.2 > >>>>>> +--- > >>>>>> +$id: http://devicetree.org/schemas/media/i2c/imx296.yaml# > >>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml# > >>>>>> + > >>>>>> +title: Sony IMX296 1/2.8-Inch CMOS Image Sensor > >>>>>> + > >>>>>> +maintainers: > >>>>>> + - Manivannan Sadhasivam > >>>>>> + > >>>>>> +description: |- > >>>>>> + The Sony IMX296 is a 1/2.9-Inch active pixel type CMOS Solid-state image > >>>>>> + sensor with square pixel array and 1.58 M effective pixels. This chip > >>>>>> + features a global shutter with variable charge-integration time. It is > >>>>>> + programmable through I2C and 4-wire interfaces. The sensor output is > >>>>>> + available via CSI-2 serial data output (1 Lane). > >>>>>> + > >>>>>> +properties: > >>>>>> + compatible: > >>>>>> + const: sony,imx296 > >>>>>> + > >>>>>> + reg: > >>>>>> + maxItems: 1 > >>>>>> + > >>>>>> + clocks: > >>>>>> + maxItems: 1 > >>>>>> + > >>>>>> + clock-names: > >>>>>> + description: > >>>>>> + Input clock for the sensor. > >>>>>> + items: > >>>>>> + - const: mclk > >>>>> > >>>>> The pin is named INCK, let's name the clock accordingly. > >>>> > >>>> Okay, I thought generic names are preferred here! > >>>> > >>>>>> + clock-frequency: > >>>>>> + description: > >>>>>> + Frequency of the mclk clock in Hertz. > >>>>> > >>>>> This shouldn't be needed, you can retrieve the clock frequency at > >>>>> runtime from the clock source. > >>>> > >>>> Unless the clock source is a fixed one! What if the clock source comes from > >>>> SoC? We need to set the rate, right? > >>> > >>> In that case, if you want to hardcode the clock in DT, the preferred way > >>> is to use the assigned-clock-rates property. Otherwise, if the driver > >>> requires a specific clock frequency, it's better to hardcode it in the > >>> driver itself. In this specific case, I think assigned-clock-rates is > >>> best as the device can support three different clock frequencies. > >> > >> Just note that if ACPI support is added to the sensor driver, you'll need > >> the clock-frequency property again, for that's the only way how the driver > >> will get the clock frequency. > > > > Why is so ? Why can't we implement of assigned-clock-rates for ACPI ? > > ACPI doesn't deal with clocks as such. So there's also no ACPI defined way > to access clocks specifically, including the frequency --- instead the > clock is controlled by an AML methods which implement power on and off > sequences for the device. It's a shortcoming of ACPI, which should be addressed at the ACPI level. We shouldn't polute the DT bindings with a clock-frequency property for this reason. -- Regards, Laurent Pinchart