From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f179.google.com (mail-yw1-f179.google.com [209.85.128.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C1D8212EE3 for ; Thu, 7 Nov 2024 14:57:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730991454; cv=none; b=sw1ngz9mHcvEElwLP3rvCg7mUJgK0er5t2ikllbOTgq1RY62i6u3Tht8thwamWaiYnk1AcQmmrmfVgGhw/KfM5Yglo32f47KJwTO15JaTK/nLzYKDI6V6n/xFJT0nY3NYtMKZ8+xGBP7PwsnLErl14fL5SCzhU1VhAeBkS57zek= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730991454; c=relaxed/simple; bh=qZ8izUSaHahLbAO7uWeGh/Gz8E/GX1hkiRPzbJN9tMY=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=dMBiO3ycjow/YJKIjuWNqSKt7oHlrg6tq8yEjAJqs0PHZu76Kl/qa9XmnCJkdljgMqDeaKZTexpXw+FuSiyPaP2DAWrj/jd4z62F2QeKdyDpNHRigfYmI3eYKfmTEIo4gAxZHd8Ar0iOfayCpDi+Y9DT9gpu9GU9uedaU0JLRIE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=amarulasolutions.com; spf=pass smtp.mailfrom=amarulasolutions.com; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b=fxTJo6Mq; arc=none smtp.client-ip=209.85.128.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=amarulasolutions.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amarulasolutions.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="fxTJo6Mq" Received: by mail-yw1-f179.google.com with SMTP id 00721157ae682-6e9f8dec3daso8645257b3.0 for ; Thu, 07 Nov 2024 06:57:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; t=1730991452; x=1731596252; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=aiuuQGCaJR6L9rbp4LJqZfhMxwW+RQ/d7RNS/+rBXDw=; b=fxTJo6MqgGoAfhP31zROnAQv2iNF3dLcyRvO3hNcsz1HIeKD6T/E1eZAwAejVhK6iL iN1uYUkLFrW84u2SD4lJ5fco7UUu7XbWZTBiFwuLTn3WH+MDNDaEQ5RLoZR1HcMJnqOz IATQBn0zm+Iw/VQmLu9ee7VHOwGjfdDJD1Zu4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730991452; x=1731596252; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=aiuuQGCaJR6L9rbp4LJqZfhMxwW+RQ/d7RNS/+rBXDw=; b=GJXmBWdYAKSFArBHfm6CC2Jm1hxyOfRTbuOVJlC9rQxCxEFifR/FZhrYdL2Ss+oyRd 0JQz6OnO6jVWqsQ7whXj1qT5XqoJzuZgE73/Q26cK3tmg1NhVIxpRP4Rnjm3TB+5Di0m Tr7YZat/POmP/I3dmrazKE+DXe0u1SOvxM2wGXdwiPtHV60JE8KDjOZcr4o3WcY4+lQk yT6C9TKVygWvxnlG03qExWlffvkoIpwbC2+gRs5fnOTBny+UKwYR7J2hmcfOp6lVhoCm Engw57LLke56mU+NejjbZUXitSeJq8bELeGOqOKLZDRHiN05P2D8EwQfFqoGZk7d/I2d II6w== X-Gm-Message-State: AOJu0YziWV/NdeX/bKXoMZQh5rNR0r3XWxA6XTdb1xr3QEO9vpPAjEl3 5JDt1S/TOUfEidpDH8tRAl3ujSPQJc00XdB64Rccvw/cdk2mMDNPb+vXdQAukoY7bXmPoDYlorl +MoWeTiFV1nSJkRvv30x5q3kmCME78AH3tpbx3A== X-Google-Smtp-Source: AGHT+IF8agBg7laXxANgHAvwKG8a08ww2rsq+nqLU8LlqFlymOUM9EIrlz0DftKlezAxcI5XDK1DcyZtsOZ0bmNH4oE= X-Received: by 2002:a05:690c:4b09:b0:6e3:b6c:d114 with SMTP id 00721157ae682-6e9d8ad309bmr466023927b3.38.1730991452024; Thu, 07 Nov 2024 06:57:32 -0800 (PST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241106090549.3684963-1-dario.binacchi@amarulasolutions.com> <20241106090549.3684963-2-dario.binacchi@amarulasolutions.com> <4bix7me5vaoyhcuffyp4btajmhy7no6ltczoesopaz2fqupyaw@fensx4nn472u> In-Reply-To: From: Dario Binacchi Date: Thu, 7 Nov 2024 15:57:21 +0100 Message-ID: Subject: Re: [PATCH v3 1/8] dt-bindings: clock: imx8m-clock: support spread spectrum clocking To: Krzysztof Kozlowski Cc: linux-kernel@vger.kernel.org, linux-amarula@amarulasolutions.com, Abel Vesa , Conor Dooley , Fabio Estevam , Krzysztof Kozlowski , Michael Turquette , Peng Fan , Pengutronix Kernel Team , Rob Herring , Sascha Hauer , Shawn Guo , Stephen Boyd , devicetree@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hello Krzysztof, On Wed, Nov 6, 2024 at 3:13=E2=80=AFPM Krzysztof Kozlowski wrote: > > On 06/11/2024 15:10, Krzysztof Kozlowski wrote: > > On Wed, Nov 06, 2024 at 09:57:57AM +0100, Dario Binacchi wrote: > >> The patch adds the DT bindings for enabling and tuning spread spectrum > >> clocking generation. > > > > We had long talks about this but nothing of it got reflected in commit > > msg. Sorry, I don't remember what I was talking in some particular patc= h > > month ago, so you will get the same questions over and over... > > > >> > >> Signed-off-by: Dario Binacchi > >> > >> --- > >> > >> Changes in v3: > >> - Added in v3 > >> - The dt-bindings have been moved from fsl,imx8m-anatop.yaml to > >> imx8m-clock.yaml. The anatop device (fsl,imx8m-anatop.yaml) is > >> indeed more or less a syscon, so it represents a memory area > >> accessible by ccm (imx8m-clock.yaml) to setup the PLLs. > >> > >> .../bindings/clock/imx8m-clock.yaml | 46 ++++++++++++++++++= + > >> 1 file changed, 46 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml = b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml > >> index c643d4a81478..7920393e518e 100644 > >> --- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml > >> +++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml > >> @@ -43,6 +43,40 @@ properties: > >> ID in its "clocks" phandle cell. See include/dt-bindings/clock/= imx8m-clock.h > >> for the full list of i.MX8M clock IDs. > >> > >> + fsl,ssc-clocks: > >> + $ref: /schemas/types.yaml#/definitions/phandle-array > >> + description: > >> + Phandles of the PLL with spread spectrum generation hardware ca= pability. > >> + minItems: 1 > >> + maxItems: 4 > > > > 1. How is it possible that you change spread spectrum of some clocks fr= om > > main Clock Controller, while this device is not a consumer of them? > > Basically this means that this device does not have these clocks but ye= t > > you claim that it needs to configure spread for them! It's contradictor= y > > to me and nohing got explained in commit msg about it. I am pretty sure > > I asked about this alrady. > > I digged my previous answer and it was pretty clear here: > > 18:44 You can, but I still have the same concerns. How this > device - which does not take any clock input, has no clocks at all - can > depend on spread spectrum of some PLLs? Thsi device does not have clocks. > 18:50 device has no clocks, I checked now third time > 18:50 If device has clocks, it must have clocks property > The device where the spread spectrum properties are to be set already contains "clocks" properties: clk: clock-controller@30380000 { compatible =3D "fsl,imx8mn-ccm"; reg =3D <0x30380000 0x10000>; interrupts =3D , ; #clock-cells =3D <1>; clocks =3D <&osc_32k>, <&osc_24m>, <&clk_ext1>, <&clk_ext2>, <&clk_ext3>, <&clk_ext4>; clock-names =3D "osc_32k", "osc_24m", "clk_ext1", "clk_ext2", "clk_ext3", "clk_ext4"; assigned-clocks =3D <&clk IMX8MN_CLK_A53_SRC>, <&clk IMX8MN_CLK_A53_CORE>, <&clk IMX8MN_CLK_NOC>, <&clk IMX8MN_CLK_AUDIO_AHB>, <&clk IMX8MN_CLK_IPG_AUDIO_ROOT>, <&clk IMX8MN_SYS_PLL3>, <&clk IMX8MN_AUDIO_PLL1>, <&clk IMX8MN_AUDIO_PLL2>; assigned-clock-parents =3D <&clk IMX8MN_SYS_PLL1_800M>, <&clk IMX8MN_ARM_PLL_OUT>, <&clk IMX8MN_SYS_PLL3_OUT>, <&clk IMX8MN_SYS_PLL1_800M>; assigned-clock-rates =3D <0>, <0>, <0>, <400000000>, <400000000>, <600000000>, <393216000>, <361267200>; }; The spread spectrum is not configurable on these clocks or, more generally, may not be configurable (only 4 PLLs have this capability). Therefore, I need the "fsl,ssc-clocks" property to list the PLLs on which I want to enable and configure spread spectrum. Furthermore, spread spectrum cannot be considered a new device but rather a property available only for some of the clocks managed by the clock controller manager (CCM). Thanks and regards, Dario > So again, you do not need this property at all. I repeated it multiple > times - you are supposed to use clocks property. > > > > > 2. Why is this array flexible in size? > > > > Best regards, > > Krzysztof > > > > Best regards, > Krzysztof > -- Dario Binacchi Senior Embedded Linux Developer dario.binacchi@amarulasolutions.com __________________________________ Amarula Solutions SRL Via Le Canevare 30, 31100 Treviso, Veneto, IT T. +39 042 243 5310 info@amarulasolutions.com www.amarulasolutions.com