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 X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0ECBAC2BB1D for ; Tue, 14 Apr 2020 20:50:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBC5A2064A for ; Tue, 14 Apr 2020 20:50:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="uvtq2ztp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2633392AbgDNUus (ORCPT ); Tue, 14 Apr 2020 16:50:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729251AbgDNUuq (ORCPT ); Tue, 14 Apr 2020 16:50:46 -0400 Received: from mail-lj1-x241.google.com (mail-lj1-x241.google.com [IPv6:2a00:1450:4864:20::241]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3241C061A0C; Tue, 14 Apr 2020 13:50:45 -0700 (PDT) Received: by mail-lj1-x241.google.com with SMTP id h25so1305326lja.10; Tue, 14 Apr 2020 13:50:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=4VidULW3sNFq1IBr5BVgYkJ2HzTTpcpxAz2X7BrAVHg=; b=uvtq2ztpgL632NvpxgxVdkS4VFpaqYP7UnlDWrRVWP0qyJK0JvIMXlY6JEF3csVS9x hWh5spAPEXlOZg6zDssOLfWPjeYofi72+ezWhkMdmzx1cJeFMzLN2qliVkSMAyC3piBw p8ArrIgjiFdvuoODf+PYy5CfebBerzULhSvEDdZX4KZjcP9XCWr9pj8sYqC6JfcC1aHe +Fnh0mHJzBMeShiR1HsagJ5HygkFgk2cSu+P12zPFIpxtz8HL+rRIz4hSAD/tXEbk0zb x1TULL6HArYkM8NaI8b9idGt/QP1kWh4p/pOr12j1lnctUXrrMSTeO5S++JLpyWD3GMx XpsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=4VidULW3sNFq1IBr5BVgYkJ2HzTTpcpxAz2X7BrAVHg=; b=VbTyety1dHdZaKXPewPW7bRvtVy0B9QK3yc4wCA7roeo3Xa8OQcDslJbHW251nubWt TvBrAjdMMi3B2W3BInwwRe+x1rsWIJCflVI7nqRA/Y8Q2Fu1WWL7482BjeoXEbdLaVTO Rl2VTSiGGeWTErK+a+52pgKKy+T0SvcntoVgk92Nf0DcJCZVZImVQXm2fXJzznVJ+21A oYC706pGQqoAnvYJKG23BWG0PNSk9GsMp09I73b8cTd+OfS/T/qQOvRH5ebb9FXeT76Y 3hRZL+M6IhFoCN3kjCTCgECswcUhTwB65fhTA4xMUZtK3Ud+cHoVXFdbL4kz9iJoNOhd xGpQ== X-Gm-Message-State: AGi0PuZFBlxK2FGf3/0gdsv9FWSXM2vJULOoi+VusaZBTu0ZvVe4t5+A BG481lUptiIKa/u+AOtEJfvMIQ0+ X-Google-Smtp-Source: APiQypILAUnA0zAmCZatBH8tHsS3tV4vXCvYDhLfn2rH0mkq6ZK2azlTQdov/cLZ9PHX+LP6y8dz4A== X-Received: by 2002:a2e:992:: with SMTP id 140mr1175625ljj.188.1586897444412; Tue, 14 Apr 2020 13:50:44 -0700 (PDT) Received: from [192.168.2.145] (ppp91-78-208-152.pppoe.mtu-net.ru. [91.78.208.152]) by smtp.googlemail.com with ESMTPSA id i18sm5608207lfo.57.2020.04.14.13.50.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Apr 2020 13:50:43 -0700 (PDT) Subject: Re: [PATCH v6 09/14] memory: tegra: Add EMC scaling support code for Tegra210 To: Thierry Reding Cc: Rob Herring , Jon Hunter , Michael Turquette , Stephen Boyd , Joseph Lo , linux-tegra@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20200409175238.3586487-1-thierry.reding@gmail.com> <20200409175238.3586487-10-thierry.reding@gmail.com> <20200414145442.GJ3593749@ulmo> From: Dmitry Osipenko Message-ID: <37c5af25-c00b-cfe0-4c13-00ac5bdef82c@gmail.com> Date: Tue, 14 Apr 2020 23:50:42 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200414145442.GJ3593749@ulmo> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org 14.04.2020 17:54, Thierry Reding пишет: ... >> I'd suggest to check how much time invocation of ktime_get() takes, at >> least it came to a surprise to me in a case of the tegra-cpuidle driver. >> >> It may be well over the emc->clkchange_delay. > > I assume that at least each invocation would take roughly the same > amount of time? Not sure. > Since we only use the value to compute the time since > the last clock change the result should always be valid. In the worst > case if ktime_get() really takes that long we may be waiting longer > than we need to, but that wouldn't be all that bad either. Changing > the EMC clock rate isn't something that you want to do a lot. Then probably should be cleaner and simpler to have a constant delay in the code? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [PATCH v6 09/14] memory: tegra: Add EMC scaling support code for Tegra210 Date: Tue, 14 Apr 2020 23:50:42 +0300 Message-ID: <37c5af25-c00b-cfe0-4c13-00ac5bdef82c@gmail.com> References: <20200409175238.3586487-1-thierry.reding@gmail.com> <20200409175238.3586487-10-thierry.reding@gmail.com> <20200414145442.GJ3593749@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200414145442.GJ3593749@ulmo> Content-Language: en-US Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: Rob Herring , Jon Hunter , Michael Turquette , Stephen Boyd , Joseph Lo , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-tegra@vger.kernel.org 14.04.2020 17:54, Thierry Reding пишет: ... >> I'd suggest to check how much time invocation of ktime_get() takes, at >> least it came to a surprise to me in a case of the tegra-cpuidle driver. >> >> It may be well over the emc->clkchange_delay. > > I assume that at least each invocation would take roughly the same > amount of time? Not sure. > Since we only use the value to compute the time since > the last clock change the result should always be valid. In the worst > case if ktime_get() really takes that long we may be waiting longer > than we need to, but that wouldn't be all that bad either. Changing > the EMC clock rate isn't something that you want to do a lot. Then probably should be cleaner and simpler to have a constant delay in the code? 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[91.78.208.152]) by smtp.googlemail.com with ESMTPSA id i18sm5608207lfo.57.2020.04.14.13.50.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Apr 2020 13:50:43 -0700 (PDT) Subject: Re: [PATCH v6 09/14] memory: tegra: Add EMC scaling support code for Tegra210 To: Thierry Reding References: <20200409175238.3586487-1-thierry.reding@gmail.com> <20200409175238.3586487-10-thierry.reding@gmail.com> <20200414145442.GJ3593749@ulmo> From: Dmitry Osipenko Message-ID: <37c5af25-c00b-cfe0-4c13-00ac5bdef82c@gmail.com> Date: Tue, 14 Apr 2020 23:50:42 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200414145442.GJ3593749@ulmo> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200414_135047_017680_DF18BF1B X-CRM114-Status: GOOD ( 12.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, Stephen Boyd , Michael Turquette , Jon Hunter , Rob Herring , Joseph Lo , linux-tegra@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org MTQuMDQuMjAyMCAxNzo1NCwgVGhpZXJyeSBSZWRpbmcg0L/QuNGI0LXRgjoKLi4uCj4+IEknZCBz dWdnZXN0IHRvIGNoZWNrIGhvdyBtdWNoIHRpbWUgaW52b2NhdGlvbiBvZiBrdGltZV9nZXQoKSB0 YWtlcywgYXQKPj4gbGVhc3QgaXQgY2FtZSB0byBhIHN1cnByaXNlIHRvIG1lIGluIGEgY2FzZSBv ZiB0aGUgdGVncmEtY3B1aWRsZSBkcml2ZXIuCj4+Cj4+IEl0IG1heSBiZSB3ZWxsIG92ZXIgdGhl IGVtYy0+Y2xrY2hhbmdlX2RlbGF5Lgo+IAo+IEkgYXNzdW1lIHRoYXQgYXQgbGVhc3QgZWFjaCBp bnZvY2F0aW9uIHdvdWxkIHRha2Ugcm91Z2hseSB0aGUgc2FtZQo+IGFtb3VudCBvZiB0aW1lPwoK Tm90IHN1cmUuCgo+IFNpbmNlIHdlIG9ubHkgdXNlIHRoZSB2YWx1ZSB0byBjb21wdXRlIHRoZSB0 aW1lIHNpbmNlCj4gdGhlIGxhc3QgY2xvY2sgY2hhbmdlIHRoZSByZXN1bHQgc2hvdWxkIGFsd2F5 cyBiZSB2YWxpZC4gSW4gdGhlIHdvcnN0Cj4gY2FzZSBpZiBrdGltZV9nZXQoKSByZWFsbHkgdGFr ZXMgdGhhdCBsb25nIHdlIG1heSBiZSB3YWl0aW5nIGxvbmdlcgo+IHRoYW4gd2UgbmVlZCB0bywg YnV0IHRoYXQgd291bGRuJ3QgYmUgYWxsIHRoYXQgYmFkIGVpdGhlci4gQ2hhbmdpbmcKPiB0aGUg RU1DIGNsb2NrIHJhdGUgaXNuJ3Qgc29tZXRoaW5nIHRoYXQgeW91IHdhbnQgdG8gZG8gYSBsb3Qu CgpUaGVuIHByb2JhYmx5IHNob3VsZCBiZSBjbGVhbmVyIGFuZCBzaW1wbGVyIHRvIGhhdmUgYSBj b25zdGFudCBkZWxheSBpbgp0aGUgY29kZT8KCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fCmxpbnV4LWFybS1rZXJuZWwgbWFpbGluZyBsaXN0CmxpbnV4LWFy bS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9t YWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFybS1rZXJuZWwK