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=-8.4 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,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 C42F0C4332D for ; Thu, 19 Mar 2020 13:03:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C26820753 for ; Thu, 19 Mar 2020 13:03:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="f/2X+PGB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727159AbgCSND5 (ORCPT ); Thu, 19 Mar 2020 09:03:57 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:42244 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727082AbgCSND4 (ORCPT ); Thu, 19 Mar 2020 09:03:56 -0400 Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 5B98EA53; Thu, 19 Mar 2020 14:03:54 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1584623034; bh=D1jU5CecA8xmxcxpuPAP4tWuL8Jb5B+/4IYit8jX3O8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f/2X+PGB9yBjdoPWDUPQluoD2ZTKNIlyTlrfleMbp07PhAnFnYboOGvf4RuR5sczj pz3qd7BHaRLVYrTMmPRH85jd7mrnmw50+rai0pAUEjPAaD3Jr/xdWmF+kqzURJ1A5w BfrL2lEgZgAp36XWI89ffk9rD1B1wz9CGhDMMLsA= Date: Thu, 19 Mar 2020 15:03:48 +0200 From: Laurent Pinchart To: Maxime Ripard Cc: Lad Prabhakar , Mauro Carvalho Chehab , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Rob Herring , Mark Rutland , Sakari Ailus , NXP Linux Team , Magnus Damm , Ezequiel Garcia , Geert Uytterhoeven , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Fabio Estevam , linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates Message-ID: <20200319130348.GC4872@pendragon.ideasonboard.com> References: <1584133954-6953-1-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <1584133954-6953-2-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com> <20200319124452.3yfcvq754vi4q2rv@gilmour.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200319124452.3yfcvq754vi4q2rv@gilmour.lan> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi Maxime, On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote: > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote: > > Use assigned-clock-rates to specify the clock rate. Also mark > > clock-frequency property as deprecated. > > > > Signed-off-by: Lad Prabhakar > > --- > > Documentation/devicetree/bindings/media/i2c/ov5645.txt | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/devicetree/bindings/media/i2c/ov5645.txt b/Documentation/devicetree/bindings/media/i2c/ov5645.txt > > index 72ad992..e62fe82 100644 > > --- a/Documentation/devicetree/bindings/media/i2c/ov5645.txt > > +++ b/Documentation/devicetree/bindings/media/i2c/ov5645.txt > > @@ -8,7 +8,7 @@ Required Properties: > > - compatible: Value should be "ovti,ov5645". > > - clocks: Reference to the xclk clock. > > - clock-names: Should be "xclk". > > -- clock-frequency: Frequency of the xclk clock. > > +- clock-frequency (deprecated): Frequency of the xclk clock. > > - enable-gpios: Chip enable GPIO. Polarity is GPIO_ACTIVE_HIGH. This corresponds > > to the hardware pin PWDNB which is physically active low. > > - reset-gpios: Chip reset GPIO. Polarity is GPIO_ACTIVE_LOW. This corresponds to > > @@ -37,7 +37,8 @@ Example: > > > > clocks = <&clks 200>; > > clock-names = "xclk"; > > - clock-frequency = <24000000>; > > + assigned-clocks = <&clks 200>; > > + assigned-clock-rates = <24000000>; > > > > vdddo-supply = <&camera_dovdd_1v8>; > > vdda-supply = <&camera_avdd_2v8>; > > clock-frequency is quite different from assigned-clock-rates though, > semantically speaking. clock-frequency is only about what the clock > frequency is, while assigned-clock-rates will change the rate as well, > and you have no idea how long it will last. The driver currently reads the clock-frequency property and then calls clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I think it's less of a hack than what we currently have. As discussed on IRC, maybe the best option in this specific case is to drop clock-frequency and assigned-clok-rates, and call clk_set_rate() with a hardcoded frequency of 24MHz in the driver, as that's the only frequency the driver supports. > If you want to retrieve that through the clock framework, then just > making clock-frequency optional is enough and falling back to > clk_get_rate on the clocks property already provided is enough. -- Regards, Laurent Pinchart