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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2C61C433EF for ; Thu, 7 Apr 2022 07:48:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242146AbiDGHuc (ORCPT ); Thu, 7 Apr 2022 03:50:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232646AbiDGHua (ORCPT ); Thu, 7 Apr 2022 03:50:30 -0400 Received: from smtp1.axis.com (smtp1.axis.com [195.60.68.17]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 023B346141; Thu, 7 Apr 2022 00:48:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; q=dns/txt; s=axis-central1; t=1649317712; x=1680853712; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=65cq+04D2t91MgXQs2FV1LSZ91INmcsG6pr3WgD2E7M=; b=bQzducTedCmQckTwZX1IlWeB9H+3fnDxErNGSv0UqoYECY1mAV0iLDGj ccIXbqu4qZpJamltH5XlBMFaBgOjaIjISpDPtXghLFWvWE1wJ/2RdTKvG kVnFMjDt8I0SAP5JyX+ZRRm0c+JhqbehKve6bUmbooP1ClbKrYhT/52B1 F8vQVcI0SShLOuvc38+4KwKI1r0Yy216y0N915mP7He93wyjx8V8yojdA mJTrcykmve5LG4kvX/BIvvNIRF3dRjdjTpw8sVjJxbcgDSHYuf1MM8Hss JxEilDw+OCQ7uYCBwLiJj1kN7AB9JOkE7aFZtNBAuoisfJCGRq1tqvwEL Q==; Date: Thu, 7 Apr 2022 09:48:29 +0200 From: Vincent Whitchurch To: Marek Szyprowski CC: "devicetree@vger.kernel.org" , "linux-samsung-soc@vger.kernel.org" , "daniel.lezcano@linaro.org" , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , kernel , "alim.akhtar@samsung.com" , "tglx@linutronix.de" , "linux-arm-kernel@lists.infradead.org" , Subject: Re: [PATCH v2 3/4] clocksource/drivers/exynos_mct: Support local-timer-index property Message-ID: <20220407074829.GA31389@axis.com> References: <20220308142410.3193729-1-vincent.whitchurch@axis.com> <20220308142410.3193729-4-vincent.whitchurch@axis.com> <226dcb1b-d141-f0d3-68c4-11d2466ca571@canonical.com> <20220311113543.GA17877@axis.com> <69be9f88-b69b-c149-4387-c5002219bf0a@canonical.com> <20220330082137.GA21079@axis.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20220330082137.GA21079@axis.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Wed, Mar 30, 2022 at 10:21:37AM +0200, Vincent Whitchurch wrote: > On Mon, Mar 21, 2022 at 09:00:08AM +0100, Marek Szyprowski wrote: > > Right, I've played a bit with MCT on some older Exynos SoCs (ARM 32bit > > based and even Exynos5433) and it looked that none of it enabled MCT FRC > > timer in their proprietary firmware. I've even proposed a patch for this > > once ([1]), but such approach has been rejected. I think that calling > > exynos4_mct_frc_start() unconditionally won't hurt. > > Thank you for looking into this. The proposal was however not to avoid > changing when exynos4_mct_frc_start() is called, but to instead skip the > write to the Timer Enable bit of the G_TCON register if it is already > set, like in the below patch. (This is needed to avoid races when the > FRC is shared between CPUs in an AMP configuration, since TCON can be > modified for other reasons from the CPU which is using the global > comparator.) > > If I understand your comment correctly, such a change should not cause > any difference at least on the platforms you looked at since there > MCT_G_TCON_START will not have been set at startup. I needed the frc-shared property anyway to prevent registration of the clock events so I followed Krzysztof's suggestion of doing this conditionally and also clearing the resume callback.