Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757525AbbGGOP7 (ORCPT ); Tue, 7 Jul 2015 10:15:59 -0400 Received: from mail-yk0-f169.google.com ([209.85.160.169]:32804 "EHLO mail-yk0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757213AbbGGOPt (ORCPT ); Tue, 7 Jul 2015 10:15:49 -0400 MIME-Version: 1.0 In-Reply-To: <20150707130732.GD18561@pengutronix.de> References: <1434605351-64592-1-git-send-email-eddie.huang@mediatek.com> <20150707130732.GD18561@pengutronix.de> From: Daniel Kurtz Date: Tue, 7 Jul 2015 22:15:29 +0800 X-Google-Sender-Auth: iochnYqNLVGh_pLAFG_P0sNk04Q Message-ID: Subject: Re: [PATCH] arm64: dts: mt8173: add clock_null To: Sascha Hauer Cc: Eddie Huang , Matthias Brugger , "open list:OPEN FIRMWARE AND..." , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , linux-mediatek@lists.infradead.org, James Liao Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2985 Lines: 76 On Tue, Jul 7, 2015 at 9:07 PM, Sascha Hauer wrote: > On Thu, Jun 18, 2015 at 01:29:11PM +0800, Eddie Huang wrote: >> Add clk_null, which represents clocks that can not / need not >> controlled by software. >> There are many clocks' parent set to clk_null. >> >> Signed-off-by: James Liao >> Signed-off-by: Eddie Huang >> --- >> Base on 4.1-rc1 >> >> Change-Id: I4db9b40d07e28f54f7bae9b676316cbd6a962124 >> --- >> arch/arm64/boot/dts/mediatek/mt8173.dtsi | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/arch/arm64/boot/dts/mediatek/mt8173.dtsi b/arch/arm64/boot/dts/mediatek/mt8173.dtsi >> index 924fdb6..4798f44 100644 >> --- a/arch/arm64/boot/dts/mediatek/mt8173.dtsi >> +++ b/arch/arm64/boot/dts/mediatek/mt8173.dtsi >> @@ -81,6 +81,12 @@ >> cpu_on = <0x84000003>; >> }; >> >> + clk_null: clk_null { >> + compatible = "fixed-clock"; >> + clock-frequency = <0>; >> + #clock-cells = <0>; >> + }; > > The discussion around this patch shows that we don't want to have this > clock in the device tree as it is not a hardware description. > > Ok, fine. Eddie, you told us that the rate of the current clk_null children > is not interesting. What's the motivation to send this patch anyway > then? Why can't you keep its children on the orphan list where they are > already now? > > Another possibility would be to instantiate the clk_null clock from C > code rather than from the device tree. This way we wouldn't put any > wrong descriptions into the device tree and still can implement the > support for the real parent clocks when we actually need them. Some device nodes, like mmc, use a clk_null phandle as one of their clocks: mmc1: mmc@11240000 { compatible = "mediatek,mt8173-mmc", "mediatek,mt8135-mmc"; reg = <0 0x11240000 0 0x1000>; interrupts = ; clocks = <&pericfg CLK_PERI_MSDC30_1>, <&clk_null>; clock-names = "source", "hclk"; status = "disabled"; }; -Dan > Sascha > > -- > Pengutronix e.K. | | > Industrial Linux Solutions | http://www.pengutronix.de/ | > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/