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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 A2B21C433FE for ; Thu, 9 Sep 2021 16:12:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 875AA6103D for ; Thu, 9 Sep 2021 16:12:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231858AbhIIQNm (ORCPT ); Thu, 9 Sep 2021 12:13:42 -0400 Received: from mail-ot1-f54.google.com ([209.85.210.54]:35736 "EHLO mail-ot1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229616AbhIIQNi (ORCPT ); Thu, 9 Sep 2021 12:13:38 -0400 Received: by mail-ot1-f54.google.com with SMTP id q11-20020a9d4b0b000000b0051acbdb2869so3158447otf.2; Thu, 09 Sep 2021 09:12:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=aoZNtEwO18E+wllQ0SRyIrGKS1rcNDEPFO0Z95WK14Y=; b=WxG0ln3eE0AY5cjzonhjal6TtIoZ4ylochobThxF7JmclySumkw631eU5+HJ+L5fYD 23YapcbkzHTsogPJvt+oemPZebZvXFcxuZ7oWUYHf0lokH8B1OXZTB1WjAzvmPJ7pPfl fTSAJ3MM4xH7/61V7K2JySwu1anuXbq0SwFBRgmnhbR4/IkoGyVvG2zxIGgi5B9VF1m0 TyU7y2f6w1zdX71Cw4koqWiVGcnF1dt99cm51mVKbDekmm5/RiXYW0+psq1l2f7iG6uj ptgWlvFeGcO2eOvIdOsPqA05Zy446X10XeTTnMAMk8ROH1uP4kIEWdY+FK6uilHZFauq 70ow== X-Gm-Message-State: AOAM530BVAmx/NW3niSEUweGre59dFjwx7lKJsovP8seS8cLmLLDsj3B XeNYP1+Ldzr6OxphRUqSpzuyrwUSmFWgsjuivQo= X-Google-Smtp-Source: ABdhPJzOFB42XBauWd2ZBpf63jL3d9OLRHTRGlthfEeFdcVqiwm6jRt5XRkPBClc7itLKanINQHlV7hb3RgKRFcABBU= X-Received: by 2002:a9d:6945:: with SMTP id p5mr520602oto.301.1631203948444; Thu, 09 Sep 2021 09:12:28 -0700 (PDT) MIME-Version: 1.0 References: <20210909034802.1708-1-dsmythies@telus.net> <223a72d91cfda9b13230e4f8cd6a29f853535277.camel@linux.intel.com> In-Reply-To: From: "Rafael J. Wysocki" Date: Thu, 9 Sep 2021 18:12:17 +0200 Message-ID: Subject: Re: [PATCH] cpufreq: intel_pstate: Override parameters if HWP forced by BIOS To: Doug Smythies Cc: "Rafael J. Wysocki" , Srinivas Pandruvada , Len Brown , Linux Kernel Mailing List , Linux PM Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 9, 2021 at 3:20 PM Doug Smythies wrote: > > On Thu, Sep 9, 2021 at 4:18 AM Rafael J. Wysocki wrote: > > > > On Thu, Sep 9, 2021 at 8:52 AM Srinivas Pandruvada > > wrote: > > > > > > On Wed, 2021-09-08 at 20:48 -0700, Doug Smythies wrote: > > > > If HWP has been already been enabled by BIOS, it may be > > > > necessary to override some kernel command line parameters. > > > > Once it has been enabled it requires a reset to be disabled. > > > > > > > > Signed-off-by: Doug Smythies > > > > --- > > > > drivers/cpufreq/intel_pstate.c | 22 ++++++++++++++++------ > > > > 1 file changed, 16 insertions(+), 6 deletions(-) > > > > > > > > diff --git a/drivers/cpufreq/intel_pstate.c > > > > b/drivers/cpufreq/intel_pstate.c > > > > index bb4549959b11..073bae5d4498 100644 > > > > --- a/drivers/cpufreq/intel_pstate.c > > > > +++ b/drivers/cpufreq/intel_pstate.c > > > > @@ -3267,7 +3267,7 @@ static int __init intel_pstate_init(void) > > > > */ > > > > if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) || > > > > intel_pstate_hwp_is_enabled()) { > > > > - hwp_active++; > > > > + hwp_active = 1; > > > Why this change? > > > > I think hwp_active can be changed to bool and then it would make sense > > to update this line. > > > > > > hwp_mode_bdw = id->driver_data; > > > > intel_pstate.attr = hwp_cpufreq_attrs; > > > > intel_cpufreq.attr = hwp_cpufreq_attrs; > > > > @@ -3347,17 +3347,27 @@ device_initcall(intel_pstate_init); > > > > > > > > static int __init intel_pstate_setup(char *str) > > > > { > > > > + /* > > > > + * If BIOS is forcing HWP, then parameter > > > > + * overrides might be needed. Only print > > > > + * the message once, and regardless of > > > > + * any overrides. > > > > + */ > > > > + if(!hwp_active > > > This part of code is from early_param, Is it possible that > > > hwp_active is not 0? > > > > Well, it wouldn't matter even if it were nonzero. This check is just > > pointless anyway. > > > > > > && boot_cpu_has(X86_FEATURE_HWP)) > > > > + if(intel_pstate_hwp_is_enabled()){ > > > > This should be > > > > if (boot_cpu_has(X86_FEATURE_HWP) && intel_pstate_hwp_is_enabled()) { > > Disagree. > This routine gets executed once per intel_pstate related grub command > line entry. The purpose of the "if(!hwp_active" part is to prevent the > printing of the message to the logs multiple times. Ah OK. Fair enough. You can do all of the checks in one conditional, though. They will be processed left-to-right anyway. But then it would be good to avoid calling intel_pstate_hwp_is_enabled() multiple times if it returns false. And having said all that I'm not sure why you are trying to make no_hwp depend on !hwp_active? I will not be taken into account anyway if intel_pstate_hwp_is_enabled() returns 'true'? So if no_hwp is covered regardless, you may move the intel_pstate_hwp_is_enabled() inside the no_load conditional. Alternatively, and I would do that, intel_pstate_hwp_is_enabled() could be evaluated earlier in intel_pstate_init() and if it returned 'true', both no_load and no_hwp would be disregarded.