Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754565AbdCFQ6m (ORCPT ); Mon, 6 Mar 2017 11:58:42 -0500 Received: from mail-io0-f195.google.com ([209.85.223.195]:36605 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753739AbdCFQ6c (ORCPT ); Mon, 6 Mar 2017 11:58:32 -0500 MIME-Version: 1.0 In-Reply-To: <20170306142850.GJ26640@tbergstrom-lnx.Nvidia.com> References: <1488295191-24038-1-git-send-email-pdeschrijver@nvidia.com> <4cf40c25-2ce9-737c-9ccb-06bc2cdb61d7@nvidia.com> <20170306083835.GF26640@tbergstrom-lnx.Nvidia.com> <6d4dd315-cab6-189d-f383-fb7523fc31bd@nvidia.com> <20170306142850.GJ26640@tbergstrom-lnx.Nvidia.com> From: Geert Uytterhoeven Date: Mon, 6 Mar 2017 16:53:48 +0100 X-Google-Sender-Auth: mIb3F4NLxTLL0ZTWiOst9n5pjQQ Message-ID: Subject: Re: [PATCH] clk: tegra: mark TEGRA210_CLK_DBGAPB as always on To: Peter De Schrijver Cc: Jon Hunter , Prashant Gaikwad , Michael Turquette , Stephen Boyd , Stephen Warren , Thierry Reding , Alexandre Courbot , linux-clk , linux-tegra@vger.kernel.org, "linux-kernel@vger.kernel.org" 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: 2444 Lines: 61 Hi Peter, On Mon, Mar 6, 2017 at 3:28 PM, Peter De Schrijver wrote: > On Mon, Mar 06, 2017 at 09:58:29AM +0000, Jon Hunter wrote: >> On 06/03/17 08:38, Peter De Schrijver wrote: >> > On Thu, Mar 02, 2017 at 05:56:49PM +0000, Jon Hunter wrote: >> >> On 28/02/17 15:19, Peter De Schrijver wrote: >> >>> This is needed to make the JTAG debugging interface work. >> >>> >> >>> Signed-off-by: Peter De Schrijver >> >>> --- >> >>> drivers/clk/tegra/clk-tegra210.c | 1 + >> >>> 1 file changed, 1 insertion(+) >> >>> >> >>> diff --git a/drivers/clk/tegra/clk-tegra210.c b/drivers/clk/tegra/clk-tegra210.c >> >>> index 9a2512a..708f5f1 100644 >> >>> --- a/drivers/clk/tegra/clk-tegra210.c >> >>> +++ b/drivers/clk/tegra/clk-tegra210.c >> >>> @@ -2680,6 +2680,7 @@ static void tegra210_cpu_clock_resume(void) >> >>> { TEGRA210_CLK_EMC, TEGRA210_CLK_CLK_MAX, 0, 1 }, >> >>> { TEGRA210_CLK_MSELECT, TEGRA210_CLK_CLK_MAX, 0, 1 }, >> >>> { TEGRA210_CLK_CSITE, TEGRA210_CLK_CLK_MAX, 0, 1 }, >> >>> + { TEGRA210_CLK_DBGAPB, TEGRA210_CLK_CLK_MAX, 0, 1 }, >> >>> { TEGRA210_CLK_TSENSOR, TEGRA210_CLK_CLK_M, 400000, 0 }, >> >>> { TEGRA210_CLK_I2C1, TEGRA210_CLK_PLL_P, 0, 0 }, >> >>> { TEGRA210_CLK_I2C2, TEGRA210_CLK_PLL_P, 0, 0 }, >> >> >> >> Should there be some dependency on say CONFIG_DEBUG_KERNEL? I am not >> >> sure we always want this on for all cases. >> > >> > Why would you not want it to be always on? >> >> Purely for power reasons. I do not know how much power keeping this > > I don't expect it to be significant but I don't have any numbers. > >> clock running consumes, but I don't like the idea of clocks running all >> the time when they are not needed. > > Problem is that in this case there is no easy way to determine if the clock > needs to be on. I had a similar issue with SH-Mobile AG5, where the power domain containing the JTAG interface is powered down. [DEBUG] ARM: dts: sh73a0: Add minimal device node for Coresight-ETM https://patchwork.kernel.org/patch/8151511/ Want to debug? Apply patch. I know it's not ideal... Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds