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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6D89C433EF for ; Tue, 2 Nov 2021 10:28:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 940CA60E74 for ; Tue, 2 Nov 2021 10:28:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231135AbhKBKbA (ORCPT ); Tue, 2 Nov 2021 06:31:00 -0400 Received: from foss.arm.com ([217.140.110.172]:60492 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230368AbhKBKa7 (ORCPT ); Tue, 2 Nov 2021 06:30:59 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 29F341FB; Tue, 2 Nov 2021 03:28:25 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.75.232]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A206B3F719; Tue, 2 Nov 2021 03:28:22 -0700 (PDT) Date: Tue, 2 Nov 2021 10:28:10 +0000 From: Mark Rutland To: Youngmin Nam Cc: krzysztof.kozlowski@canonical.com, will@kernel.org, daniel.lezcano@linaro.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, pullip.cho@samsung.com, hoony.yu@samsung.com, hajun.sung@samsung.com, myung-su.cha@samsung.com, kgene@kernel.org Subject: Re: [PATCH v2 1/2] clocksource/drivers/exynos_mct_v2: introduce Exynos MCT version 2 driver for next Exynos SoC Message-ID: <20211102102802.GA16545@C02TD0UTHF1T.local> References: <20211102001122.27516-1-youngmin.nam@samsung.com> <20211102001122.27516-2-youngmin.nam@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211102001122.27516-2-youngmin.nam@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 02, 2021 at 09:11:21AM +0900, Youngmin Nam wrote: > Exynos MCT version 2 is composed of 1 FRC and 12 comparators. > There are no global timer and local timer anymore. > The 1 of 64bit FRC serves as "up-counter"(not "comparators"). > The 12 comaprators(not "counter") can be used as per-cpu event timer > so that it can support upto 12 cores. > And a RTC source can be used as backup clock source. [...] > +static int exynos_mct_starting_cpu(unsigned int cpu) > +{ > + struct mct_clock_event_device *mevt = per_cpu_ptr(&percpu_mct_tick, cpu); > + struct clock_event_device *evt = &mevt->evt; > + > + snprintf(mevt->name, sizeof(mevt->name), "mct_comp%d", cpu); > + > + evt->name = mevt->name; > + evt->cpumask = cpumask_of(cpu); > + evt->set_next_event = exynos_comp_set_next_event; > + evt->set_state_periodic = mct_set_state_periodic; > + evt->set_state_shutdown = mct_set_state_shutdown; > + evt->set_state_oneshot = mct_set_state_shutdown; > + evt->set_state_oneshot_stopped = mct_set_state_shutdown; > + evt->tick_resume = mct_set_state_shutdown; > + evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; > + evt->rating = 500; /* use value higher than ARM arch timer */ Previously Will asked you to try CLOCK_EVT_FEAT_PERCPU here, and to set the C3STOP flag on the arch timer via the DT when necessary, rather than trying to override the arch timer like this: https://lore.kernel.org/r/20211027073458.GA22231@willie-the-truck There are a bunch of things that depend on the architected timer working as a clocksource (e.g. vdso, kvm), and it *should* work as a lock clockevent_device if configured correctly, and it's much more consistent with *everyone else* to use the arhcitected timer by default. Please try as Will suggested above, so that this works from day one. Thanks, Mark.