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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 82DA6C3DA49 for ; Thu, 18 Jul 2024 09:26:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=H9lqurF44sw+1ADpaOF53oyO/Rm557oDMNgtt5UbkDE=; b=XlZfuIsdQjeVSVXGMUchLKN3fj fK1o+K7JygAUkzk2qp6swZ1/OWRzERVNpRuklNb1k2lI809VhS1Vshm8FT1sUFT2TUx652GJx8G5P xI7JHeO+u3nDWN4ceZRy/Hkwg7yEl/1VgByG8Ci1ZgHUv5YZpRodtmxbKf0NpvVCuInQfr65vnDNd pvtno7leASMO83gQuFYCwZqps6q47DnBMDbFSzCbgaaLCAQSmb7u3+JasVpcGSebnE4L9NC5LEYY/ rSKqEJ5Gls4IZQXwzRuL2uT164W0K4o4bLd8bgkF6kn69c2v/dvXeEl6XEggrvl4g1C2UyGLJR9lr 8s9wd7ew==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sUNOo-0000000GYNX-22bo; Thu, 18 Jul 2024 09:26:06 +0000 Received: from gloria.sntech.de ([185.11.138.130]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sUNOS-0000000GYIH-2e5p; Thu, 18 Jul 2024 09:25:46 +0000 Received: from i5e860d09.versanet.de ([94.134.13.9] helo=diego.localnet) by gloria.sntech.de with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1sUNOD-0003Jt-IN; Thu, 18 Jul 2024 11:25:29 +0200 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Conor Dooley Cc: mturquette@baylibre.com, sboyd@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Subject: Re: [PATCH v2 1/3] dt-bindings: clocks: add binding for voltage-controlled-oscillators Date: Thu, 18 Jul 2024 11:25:28 +0200 Message-ID: <3178118.zE8UqtGg2D@diego> In-Reply-To: <20240716-deceiving-saucy-851fb2303c1f@spud> References: <20240715110251.261844-1-heiko@sntech.de> <20240715110251.261844-2-heiko@sntech.de> <20240716-deceiving-saucy-851fb2303c1f@spud> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240718_022544_705678_850F3654 X-CRM114-Status: GOOD ( 33.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Conor, Am Dienstag, 16. Juli 2024, 18:15:08 CEST schrieb Conor Dooley: > On Mon, Jul 15, 2024 at 01:02:49PM +0200, Heiko Stuebner wrote: > > In contrast to fixed clocks that are described as ungateable, boards > > sometimes use additional oscillators for things like PCIe reference > > clocks, that need actual supplies to get enabled and enable-gpios to be > > toggled for them to work. > > > > This adds a binding for such oscillators that are not configurable > > themself, but need to handle supplies for them to work. > > > > In schematics they often can be seen as > > > > ---------------- > > Enable - | 100MHz,3.3V, | - VDD > > | 3225 | > > GND - | | - OUT > > ---------------- > > > > or similar. The enable pin might be separate but can also just be tied > > to the vdd supply, hence it is optional in the binding. > > > > Signed-off-by: Heiko Stuebner > > --- > > .../bindings/clock/voltage-oscillator.yaml | 49 +++++++++++++++++++ > > 1 file changed, 49 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/clock/voltage-oscillator.yaml > > > > diff --git a/Documentation/devicetree/bindings/clock/voltage-oscillator.yaml b/Documentation/devicetree/bindings/clock/voltage-oscillator.yaml > > new file mode 100644 > > index 0000000000000..8bff6b0fd582e > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/clock/voltage-oscillator.yaml > > @@ -0,0 +1,49 @@ > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/clock/voltage-oscillator.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Voltage controlled oscillator > > Voltage controlled oscillator? Really? That sounds far too similar to a > VCO to me, and the input voltage here (according to the description at > least) does not affect the frequency of oscillation. That naming was suggested by Stephen in v1 [0] . Of course the schematics for the board I have only describe it as "100MHz,3.3V,3225" , thumbing through some mouser parts matching that only mentions "supply voltage" in their datasheets but not a dependency between rate and voltage. [0] https://lore.kernel.org/linux-arm-kernel/b3c450a94bcb4ad0bc5b3c7ee8712cb8.sboyd@kernel.org/ > Why the dedicated binding, rather than adding a supply and enable-gpio > to the existing "fixed-clock" binding? I suspect that a large portion of > "fixed-clock"s actually require a supply that is (effectively) > always-on. I guess there are three aspects: - I do remember discussions in the past about not extending generic bindings with device-specific stuff. I think generic power-sequences were the topic back then, though that might have changed over time? - There are places that describe "fixed-clock" as "basic fixed-rate clock that cannot gate" [1] - Stephen also suggested a separate binding [2] With the fixed-clock being sort of the root for everything else on most systems, I opted to leave it alone. I guess if the consenus really is that this should go there, I can move it, but discussion in v1 Interestingly the fixed clock had a gpios property 10 years ago [3] :-) . [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/clk/clk-fixed-rate.c#n18 [2] https://lore.kernel.org/linux-arm-kernel/68f6dc44a8202fd83792e58aea137632.sboyd@kernel.org/ [3] https://lore.kernel.org/linux-kernel//20140515064420.9521.47383@quantum/T/#t Heiko > > + > > +maintainers: > > + - Heiko Stuebner > > + > > +properties: > > + compatible: > > + const: voltage-oscillator > > + > > + "#clock-cells": > > + const: 0 > > + > > + clock-frequency: true > > + > > + clock-output-names: > > + maxItems: 1 > > + > > + enable-gpios: > > + description: > > + Contains a single GPIO specifier for the GPIO that enables and disables > > + the oscillator. > > + maxItems: 1 > > + > > + vdd-supply: > > + description: handle of the regulator that provides the supply voltage > > + > > +required: > > + - compatible > > + - "#clock-cells" > > + - clock-frequency > > + - vdd-supply > > + > > +additionalProperties: false > > + > > +examples: > > + - | > > + voltage-oscillator { > > + compatible = "voltage-oscillator"; > > + #clock-cells = <0>; > > + clock-frequency = <1000000000>; > > + vdd-supply = <®_vdd>; > > + }; > > +... >