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 EED09C55177 for ; Sun, 2 Aug 2026 16:46:15 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Z0iZTbjCu+gfJgRQt1mMeYmu8eVDQV+4fRYL8uwZYK4=; b=hkUKwVCbfqrBcF7s/XS7gr4PVx CfDLdnE66sHf3g17b8LQBXEh2lVvYxgV3buc5VyAFG0HOSdJTplG8CTRC5N/2lZUIhylF2lNlorR9 MuLXSe/rnmhOvvUGVzlyw5zHpqum+fWqnCGY5wiLCwP4I7Rz76TQuraMKwwT5dd1vlWHrHUlKbe3A RU2F2pWq3ziDeKoSl0wbY2SyXvDffFCRMlhuvWzYUS62qvAUsxhLySrLGYxADst1OczJI3n392OR+ S8uDv2qFznr4flUCRsINVMTXst8GnQsqskh9uVgpQw9AasVw5kXTKSrXQRhEYdI4NQzPzGoCE6ixS 7focZbsw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wqXym-0000000FmpV-1ZfI; Sun, 02 Aug 2026 15:19:56 +0000 Received: from vps0.lunn.ch ([156.67.10.101]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wqXyk-0000000Fmox-09eN; Sun, 02 Aug 2026 15:19:55 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=Z0iZTbjCu+gfJgRQt1mMeYmu8eVDQV+4fRYL8uwZYK4=; b=u/0i0lfybCTJSYExtr1Uw0vxtn Nx7C6sUcYSujLOoYXNwABTyDo1VUA5n7QDbPAnLqCRLrVGi6SQzBP2DhJAZBVAlmf7yVG7FUFcfgJ jevye1Vhb3DEE4iNL7RwlkajiQRndE69KmejwyJaSEYkBs56K0bBbitBBzCNhsqTUkrc=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1wqXyT-00FaSJ-CD; Sun, 02 Aug 2026 17:19:37 +0200 Date: Sun, 2 Aug 2026 17:19:37 +0200 From: Andrew Lunn To: Coia Prant Cc: Heiko =?iso-8859-1?Q?St=FCbner?= , Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Vinod Koul , Maxime Chevallier , Maxime Coquelin , Alexandre Torgue , Lad Prabhakar , Romain Gantois , Heiner Kallweit , Neil Armstrong , Russell King , Shawn Lin , David Heidelberg , netdev@vger.kernel.org, linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org, linux-stm32@st-md-mailman.stormreply.com, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH v2 05/10] arm64: dts: rockchip: rk3568: add XPCS and fixed-clock nodes Message-ID: <4106e359-aec0-4f38-b74f-e9757a48eebb@lunn.ch> References: <20260801142244.679437-2-coiaprant@gmail.com> <20260801142244.679437-7-coiaprant@gmail.com> <2847036.GUH7pLUipS@diego> <0e9d16df-7332-446b-9321-ce3de3111ffa@lunn.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260802_081954_097672_44C62774 X-CRM114-Status: GOOD ( 21.70 ) 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 On Sun, Aug 02, 2026 at 11:28:12AM +0800, Coia Prant wrote: > Hi Andrew, > > Thanks for the detailed questions. I've looked into the clock tree > more carefully. > > > Do you have documentation for these Combo PHYs? > > Yes, the information is available in the Rockchip RK3568 TRM > (Technical Reference Manual). > The relevant clock tree details are also mentioned in upstream > discussions and patches. > > > Can these clocks be enabled/disabled? > > The 100 MHz input clock to the Combo PHY is a prerequisite for its operation. > It is generated by the SoC's internal PPLL and fed to the PHY through > a fixed divider. > It is not a gate that can be individually enabled or disabled by > software; it is part of the > PHY's fundamental operating conditions. > > > And how is the Combo PHY fed with a clock? Does it have an external oscillator/crystal? > > The Combo PHY is fed by an internal 100 MHz clock derived from the PPLL. > Specifically, the PPLL runs at 200 MHz, and this is divided by 2 to provide the > 100 MHz clock input to the Combo PHY. > So, it does not use an external oscillator or crystal for its main > reference clock; > it's generated internally by the SoC. > > To summarize: > - The 125 MHz clocks (xpcs_gmac0_clk / xpcs_gmac1_clk) are outputs > from the Combo PHY. > - The Combo PHY itself is clocked by an internal 100 MHz clock from the PPLL. > - This is all internal to the SoC and does not involve a board-level oscillator. > > I hope this clarifies the clock architecture. So what is the purpose of the fixed-clock DT nodes? If you want to describe the hardware, is the PPLL in DT? Should you then add a fixed divider to give 100MHz? And then a fixed multiplier to give 125MHz? Andrew