From patchwork Fri Jun 19 14:30:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 11614519 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DCE42912 for ; Fri, 19 Jun 2020 16:10:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C522F217D9 for ; Fri, 19 Jun 2020 16:10:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592583037; bh=hqm+PvpyNvRgtUuOmX+tGUJ1Q+NRdPlT+Ae6mSKW1LY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UIDV3IR4ToAbj54egbFO/pgiK9hKB7Ee92EUjJ+TgXpLugOrVhxMB9xz21vSG960S KgoVKJnXogzSVepyUC3mixnpGaOFo9loFIbnkngZTcbuTsn9KkGPGmBH0YvjBa6EAo Kirnor5MD53MBoNbRc/g+gCrKGWyEu0VAXo3s4v0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391446AbgFSPGc (ORCPT ); Fri, 19 Jun 2020 11:06:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:35646 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390911AbgFSPGb (ORCPT ); Fri, 19 Jun 2020 11:06:31 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 373D621835; Fri, 19 Jun 2020 15:06:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592579190; bh=hqm+PvpyNvRgtUuOmX+tGUJ1Q+NRdPlT+Ae6mSKW1LY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lNH/jPes+NqrRJnr5L9ugTRJJm94WZz0ft/GI96Q/NAb1d2UkrwQgu9VrUqIZI4Rq SVUkJpas+4ma4mchQ9AD01g7yKSO+4Sx/XGQnrXyZEM1/qHYaNt9gDbZiY0fOeZy1Q sFl+wpGHB2JIxfFeD5RJtgHT3TjqcKBfhjZqRd1w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Serge Semin , Alexey Malahov , Thomas Bogendoerfer , Paul Burton , Ralf Baechle , Alessandro Zummo , Alexandre Belloni , Arnd Bergmann , Rob Herring , linux-mips@vger.kernel.org, linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, Daniel Lezcano , Sasha Levin Subject: [PATCH 5.4 042/261] clocksource: dw_apb_timer: Make CPU-affiliation being optional Date: Fri, 19 Jun 2020 16:30:53 +0200 Message-Id: <20200619141651.948460504@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141649.878808811@linuxfoundation.org> References: <20200619141649.878808811@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org From: Serge Semin [ Upstream commit cee43dbf2ee3f430434e2b66994eff8a1aeda889 ] Currently the DW APB Timer driver binds each clockevent timers to a particular CPU. This isn't good for multiple reasons. First of all seeing the device is placed on APB bus (which makes it accessible from any CPU core), accessible over MMIO and having the DYNIRQ flag set we can be sure that manually binding the timer to any CPU just isn't correct. By doing so we just set an extra limitation on device usage. This also doesn't reflect the device actual capability, since by setting the IRQ affinity we can make it virtually local to any CPU. Secondly imagine if you had a real CPU-local timer with the same rating and the same CPU-affinity. In this case if DW APB timer was registered first, then due to the clockevent framework tick-timer selection procedure we'll end up with the real CPU-local timer being left unselected for clock-events tracking. But on most of the platforms (MIPS/ARM/etc) such timers are normally embedded into the CPU core and are accessible with much better performance then devices placed on APB. For instance in MIPS architectures there is r4k-timer, which is CPU-local, assigned with the same rating, and normally its clockevent device is registered after the platform-specific one. So in order to fix all of these issues let's make the DW APB Timer CPU affinity being optional and deactivated by passing a negative CPU id, which will effectively set the DW APB clockevent timer cpumask to 'cpu_possible_mask'. Signed-off-by: Serge Semin Cc: Alexey Malahov Cc: Thomas Bogendoerfer Cc: Paul Burton Cc: Ralf Baechle Cc: Alessandro Zummo Cc: Alexandre Belloni Cc: Arnd Bergmann Cc: Rob Herring Cc: linux-mips@vger.kernel.org Cc: linux-rtc@vger.kernel.org Cc: devicetree@vger.kernel.org Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20200521204818.25436-5-Sergey.Semin@baikalelectronics.ru Signed-off-by: Sasha Levin --- drivers/clocksource/dw_apb_timer.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c index 654766538f93..10ce69548f1b 100644 --- a/drivers/clocksource/dw_apb_timer.c +++ b/drivers/clocksource/dw_apb_timer.c @@ -222,7 +222,8 @@ static int apbt_next_event(unsigned long delta, /** * dw_apb_clockevent_init() - use an APB timer as a clock_event_device * - * @cpu: The CPU the events will be targeted at. + * @cpu: The CPU the events will be targeted at or -1 if CPU affiliation + * isn't required. * @name: The name used for the timer and the IRQ for it. * @rating: The rating to give the timer. * @base: I/O base for the timer registers. @@ -257,7 +258,7 @@ dw_apb_clockevent_init(int cpu, const char *name, unsigned rating, dw_ced->ced.max_delta_ticks = 0x7fffffff; dw_ced->ced.min_delta_ns = clockevent_delta2ns(5000, &dw_ced->ced); dw_ced->ced.min_delta_ticks = 5000; - dw_ced->ced.cpumask = cpumask_of(cpu); + dw_ced->ced.cpumask = cpu < 0 ? cpu_possible_mask : cpumask_of(cpu); dw_ced->ced.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ; dw_ced->ced.set_state_shutdown = apbt_shutdown;