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=ham 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 0C171C43331 for ; Tue, 24 Mar 2020 16:12:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D11B7208E0 for ; Tue, 24 Mar 2020 16:12:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="jhEyVSol" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728970AbgCXQMk (ORCPT ); Tue, 24 Mar 2020 12:12:40 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:45828 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728910AbgCXQM0 (ORCPT ); Tue, 24 Mar 2020 12:12:26 -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 0CB43308; Tue, 24 Mar 2020 17:12:23 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1585066344; bh=h9AU8lIpV7OHn82ip0Jw12bYSRW82NU8UY8yuWnDD/A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jhEyVSolpqtVGQVGQ7ZsK5akEab88MiGhWEvbC4a6HAJothOGvP7rBw4+LTm2kv0x y1e8bNcrGWMkklZyBCMKRgPkxOhFV4YXN0t5YMPn8WIZ9z+KUQsjYmK/kUnZKeJZNw oyuI3ypKkx8sJze7gPlnVR/a+roJIFn2QjyRGBCw= Date: Tue, 24 Mar 2020 18:12:21 +0200 From: Laurent Pinchart To: "Lad, Prabhakar" Cc: Maxime Ripard , Mark Rutland , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Pengutronix Kernel Team , Ezequiel Garcia , Sascha Hauer , Magnus Damm , Lad Prabhakar , LKML , Linux-Renesas , Rob Herring , Geert Uytterhoeven , Sakari Ailus , Shawn Guo , Mauro Carvalho Chehab , Fabio Estevam , linux-media , LAK , NXP Linux Team Subject: Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates Message-ID: <20200324161221.GA27805@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> <20200319130348.GC4872@pendragon.ideasonboard.com> <20200324154045.whiy6uvlg2mrjv5a@gilmour.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Prabhakar, On Tue, Mar 24, 2020 at 04:04:43PM +0000, Lad, Prabhakar wrote: > On Tue, Mar 24, 2020 at 3:40 PM Maxime Ripard wrote: > > On Thu, Mar 19, 2020 at 01:17:51PM +0000, Lad, Prabhakar wrote: > > > On Thu, Mar 19, 2020 at 1:04 PM Laurent Pinchart wrote: > > > > 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. > > > > > > > Does this mean any driver which has a fixed clock requirement shouldn't be a > > > DT property and should be just handled by the drivers internally ? > > > > It's hard to give a generic policy, but here, the hardware is pretty > > flexible since it can deal with anything between 6MHz to 50-something > > MHz, it's the driver that chooses to enforce a 24MHz and be pedantic > > about it, so it's up to the driver to enforce that policy, not to the > > DT since it's essentially a software limitation, not a hardware one. > > Thank you for the clarification, Ill drop patches 1-4 from this series. That's the whole series... :-) I think you should keep patch 1/4 but just remove the clock-frequency from the bindings, then remove it from the DT files, and patch the driver to set the clock rate to 24MHz unconditionally in patch 4/4. -- Regards, Laurent Pinchart